Custom Truck One Source SC 13D/A / ECP ControlCo ownership change

United States

Securities and Exchange Commission

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

Information to be Included in Statements Filed Pursuant to § 240.13d-1(a) and Amendments Thereto Filed Pursuant to § 240.13d-2(a)

Under the Securities Exchange Act of 1934

(Amendment No. 6)*

Custom Truck One Source, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

23204X103

(CUSIP Number)

Christopher M. Leininger, Esq.

c/o ECP

40 Beechwood Road

Summit, NJ 07901

(973) 671-6100

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

December 6, 2024

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. ☐

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See § 240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 23204X103

13D

Page 1 of 20 Pages

1	Names of Reporting Persons ECP ControlCo, LLC
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person OO (Limited Liability Company)

CUSIP No. 23204X103

13D

Page 2 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners III, LLC
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person OO (Limited Liability Company)

CUSIP No. 23204X103

13D

Page 3 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners GP III, LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 4 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners III, LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 5 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners III-A, LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 6 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners III-B, LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 7 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners III-C, LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 8 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners III-D, LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 9 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners GP III Co-Investment (NESCO), LLC
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person OO (Limited Liability Company)

CUSIP No. 23204X103

13D

Page 10 of 20 Pages

1	Names of Reporting Persons Energy Capital Partners III (NESCO Co-Invest), LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 11 of 20 Pages

1	Names of Reporting Persons ECP Starlight Public GP, LLC
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person OO (Limited Liability Company)

CUSIP No. 23204X103

13D

Page 12 of 20 Pages

1	Names of Reporting Persons ECP Starlight Guarantor (Public), LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 13 of 20 Pages

1	Names of Reporting Persons NESCO Holdings GP, LLC
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

20,287,270

Sole Dispositive Power

Shared Dispositive Power

20,287,270

11	Aggregate Amount Beneficially Owned by Each Reporting Person 20,287,270
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 8.7%
14	Type of Reporting Person OO (Limited Liability Company)

CUSIP No. 23204X103

13D

Page 14 of 20 Pages

1	Names of Reporting Persons NESCO Holdings, LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

16,740,518

Sole Dispositive Power

Shared Dispositive Power

16,740,518

11	Aggregate Amount Beneficially Owned by Each Reporting Person 16,740,518
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 7.2%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 15 of 20 Pages

1	Names of Reporting Persons ECP Cardinal Holdings, LP
2	Check the Appropriate Box if a Member of a Group	(a) ☐ (b) ☐
3	SEC Use Only
4	Source of Funds (See Instructions) OO
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e) ☐
6	Citizenship or Place of Organization Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY EACH

REPORTING

PERSON

WITH

Sole Voting Power

Shared Voting Power

3,546,752

Sole Dispositive Power

Shared Dispositive Power

3,546,752

11	Aggregate Amount Beneficially Owned by Each Reporting Person 3,546,752
12	Check if the Aggregate Amount in Row (11) Excludes Certain Shares ☐
13	Percent of Class Represented by Amount in Row (11) 1.5%
14	Type of Reporting Person PN

CUSIP No. 23204X103

13D

Page 16 of 20 Pages

Explanatory Note

This Amendment No. 6 to Schedule 13D (this “Amendment No. 6”) amends and supplements the statement on Schedule 13D filed with the United States Securities and Exchange Commission (the “SEC”) on August 7, 2019, as amended to date (the “Statement”), relating to the common stock, par value $0.0001 per share (the “Common Stock”), of Custom Truck One Source, Inc. (the “Issuer”). Capitalized terms used herein without definition shall have the meaning set forth in the Statement.

Item 5.

Interest in Securities of the Issuer.

Item 5 of the Statement is hereby amended and restated in its entirety as follows:

(a) – (b)

The following sets forth, as of the date of this Statement, the aggregate number of shares of Common Stock and percentage of shares of Common Stock beneficially owned by each of the Reporting Persons, as well as the number of shares of Common Stock as to which each Reporting Person has the sole power to vote or to direct the vote, shared power to vote or to direct the vote, sole power to dispose or to direct the disposition of, or shared power to dispose or to direct the disposition of, as of the date hereof, based on 233,432,467 shares of Common Stock outstanding as of October 28, 2024, as disclosed in the Issuer’s Quarterly Report on Form 10-Q as filed with the Securities and Exchange Commission on October 30, 2024.

Reporting Person	Amount beneficially owned		Percent of class			Sole power to vote or to direct the vote		Shared power to vote or to direct the vote		Sole power to dispose or to direct the disposition		Shared power to dispose or to direct the disposition
ECP ControlCo, LLC		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners III, LLC		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners GP III, LP		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners III, LP		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners III-A, LP		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners III-B, LP		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners III-C, LP		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners III-D, LP		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners GP III Co-Investment (NESCO), LLC		20,287,270		8.7	%		0		20,287,270		0		20,287,270
Energy Capital Partners III (NESCO Co-Invest), LP		20,287,270		8.7	%		0		20,287,270		0		20,287,270
ECP Starlight Public GP, LLC		20,287,270		8.7	%		0		20,287,270		0		20,287,270
ECP Starlight Guarantor (Public), LP		20,287,270		8.7	%		0		20,287,270		0		20,287,270
NESCO Holdings GP, LLC		20,287,270		8.7	%		0		20,287,270		0		20,287,270
NESCO Holdings, LP		16,740,518		7.2	%		0		16,740,518		0		16,740,518
ECP Cardinal Holdings, LP		3,546,752		1.5	%		0		3,546,752		0		3,546,752

CUSIP No. 23204X103

13D

Page 17 of 20 Pages

ECP Cardinal Holdings, LP and NESCO Holdings, LP are the record holders of 3,546,752 and 16,740,518 shares of Common Stock, respectively.

ECP ControlCo, LLC is controlled by its board of managers, which consists of Douglas Kimmelman, Peter Labbat, Tyler Reeder, Rahman D’Argenio, Raoul Hughes and Xavier Robert (together, the “ECP Managers”), all of whom collectively share the power to vote and dispose of the securities beneficially owned by ECP ControlCo, LLC. As a result of the relationships described below, each of the ECP Managers may be deemed to share beneficial ownership of the securities described herein. Each individual disclaims beneficial ownership of such securities.

ECP ControlCo, LLC is the managing member of Energy Capital Partners III, LLC, which is the general partner of (i) Energy Capital Partners GP III, LP, which is the general partner of each of Energy Capital Partners III, LP, Energy Capital Partners III-A, LP, Energy Capital Partners III-B, LP, Energy Capital Partners III-C, LP, and Energy Capital Partners III-D, LP, which are the sole members of ECP Starlight Public GP, LLC, which is the general partner of ECP Starlight Guarantor (Public), LP, and (ii) Energy Capital Partners GP III Co-Investment (NESCO), LLC, which is the general partner of Energy Capital Partners III (NESCO Co-Invest), LP. ECP Starlight Guarantor (Public), LP and Energy Capital Partners III (NESCO Co-Invest), LP are the sole members of NESCO Holdings GP, LLC, which is the general partner of each of ECP Cardinal Holdings, LP and NESCO Holdings, LP. Each of the foregoing entities may be deemed to share beneficial ownership of the securities held of record by ECP Cardinal Holdings, LP and NESCO Holdings, LP.

(c) From November 18, 2024, to December 6, 2024, ECP Cardinal Holdings, LP and NESCO Holdings, LP disposed of an aggregate of 3,097,609 shares of Common Stock in a series of open-market transactions. Details by date, listing the number of shares of Common Stock disposed of and the weighted average price per share, are provided below. The Reporting Persons undertake to provide, upon request by the staff of the SEC or the Issuer, full information regarding the number of shares sold at each separate price for each transaction.

Date	Shares Disposed of by ECP Cardinal Holdings, LP		Shares Disposed of by NESCO Holdings, LP		Weighted Average Price
November 18, 2024		9,367		44,159	$	5.0569
November 19, 2024		5,769		27,198	$	5.0291
November 20, 2024		7,229		34,079	$	5.1023
November 21, 2024		10,842		51,111	$	5.2491
November 22, 2024		26,290		123,941	$	5.6286
November 25, 2024		18,298		86,258	$	5.8984
November 26, 2024		11,142		52,527	$	5.7794
November 29, 2024		9,581		45,171	$	5.9880
December 2, 2024		11,598		54,677	$	5.8199
December 4, 2024		8,819		41,575	$	5.7096
December 5, 2024		8,550		40,308	$	5.7703
December 6, 2024		3,346		15,774	$	5.7300
December 6, 2024		410,843		1,939,157	$	5.1600
TOTAL:		541,674		2,555,935

(d) None.

(e) Not applicable.

CUSIP No. 23204X103

13D

Page 18 of 20 Pages

SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Statement is true, complete and correct.

Date: December 10, 2024

	ECP ControlCo, LLC

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

	Energy Capital Partners III, LLC

	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

	Energy Capital Partners GP III, LP

	By:	Energy Capital Partners III, LLC, its general partner
	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

	Energy Capital Partners III, LP

	By:	Energy Capital Partners GP III, LP, its general partner
	By:	Energy Capital Partners III, LLC, its general partner
	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

	Energy Capital Partners III-A, LP

	By:	Energy Capital Partners GP III, LP, its general partner
	By:	Energy Capital Partners III, LLC, its general partner
	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

CUSIP No. 23204X103

13D

Page 19 of 20 Pages

	Energy Capital Partners III-B, LP

	By:	Energy Capital Partners GP III, LP, its general partner
	By:	Energy Capital Partners III, LLC, its general partner
	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

	Energy Capital Partners III-C, LP

	By:	Energy Capital Partners GP III, LP, its general partner
	By:	Energy Capital Partners III, LLC, its general partner
	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

	Energy Capital Partners III-D, LP

	By:	Energy Capital Partners GP III, LP, its general partner
	By:	Energy Capital Partners III, LLC, its general partner
	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

	Energy Capital Partners GP III Co-Investment (NESCO), LLC

	By:	Energy Capital Partners III, LLC, its general partner
	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

	Energy Capital Partners III (NESCO Co-Invest), LP

	By:	Energy Capital Partners GP III Co-Investment (NESCO), LLC
	By:	Energy Capital Partners III, LLC, its general partner
	By:	ECP ControlCo, LLC, its managing member

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	Managing Member

CUSIP No. 23204X103

13D

Page 20 of 20 Pages

	ECP Starlight Public GP, LLC

	By:	/s/ Christopher M. Leininger
	Name:	Christopher M. Leininger
	Title:	Executive Vice President & General Counsel

	ECP Starlight Guarantor (Public), LP

	By:	ECP Starlight Public GP, LLC, its general partner

	By:	/s/ Christopher M. Leininger
	Name:	Christopher M. Leininger
	Title:	Executive Vice President & General Counsel

	NESCO Holdings GP, LLC

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	President

	NESCO Holdings, LP

	By:	NESCO Holdings GP, LLC, its general partner

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	President

	ECP Cardinal Holdings, LP

	By:	NESCO Holdings GP, LLC, its general partner

	By:	/s/ Rahman D’Argenio
	Name:	Rahman D’Argenio
	Title:	President

Custom Truck One Source (CTOS) SC 13D/ACustom Truck One Source / ECP ControlCo ownership change