GUARANTY DATED AUGUST 12, 2003 BETWEEN FIRST ENERGY CORP. AND ATLAS RESOURCES, INC. TO GAS PURCHASE AGREEMENT DATED MARCH 31, 1999 BETWEEN NORTHEAST OHIO GAS MARKETING, INC., AND ATLAS ENERGY GROUP, INC., ATLAS RESOURCES, INC., AND RESOURCE ENERGY, INC

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Exhibit 10(d)

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GUARANTY DATED AUGUST 12, 2003

BETWEEN FIRST ENERGY CORP. AND ATLAS RESOURCES, INC.

TO GAS PURCHASE AGREEMENT DATED MARCH 31, 1999

BETWEEN NORTHEAST OHIO GAS MARKETING, INC., AND ATLAS

ENERGY GROUP, INC., ATLAS RESOURCES, INC., AND RESOURCE

ENERGY, INC.

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FirstEnergy(R) 76 South Main St.

Akron, Ohio 44308

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1-800-633-4766

Guaranty dated as of August 12, 2003 by and between FirstEnergy Corp., an

Ohio corporation, with its principal place of business at 76 South Main Street,

Akron, OH 44308 ("Guarantor") and Atlas Resources Inc., a Pennsylvania

corporation, with its principal place of business at 311 Rouser Rd., Coraopolis,

PA 15108 ("Seller"). Seller, together with its affiliates Atlas Energy Group,

Inc., an Ohio Corporation, Resource Energy, Inc., a Delaware corporation, and

Viking Resources Corporation, an Ohio Corporation, entered into a Gas Purchase

Agreement for the purchase and sale of natural gas ("Sales Agreement") to

FirstEnergy Solutions Corp.,("Customer"), a subsidiary of the Guarantor.

In consideration thereof, and as an inducement for the extension of credit

by the Seller to the Customer, the Guarantor hereby absolutely and

unconditionally guarantees to the Seller, its permitted successors and assigns

pursuant to this letter (this "Guaranty"), the prompt payment (within three (3)

business days of demand by the Seller) of any and all amounts that are or may

hereafter become due and payable (taking into account all applicable grace

periods) from the Customer to the Seller by reason of the Sales Agreement (the

"Obligations"), to fully perform the Sales Agreement, as well as any

indebtedness under the Sales Agreement (regardless of whether such indebtedness

be in the form of book accounts, promissory notes, trade acceptances, checks,

drafts, or other evidence of indebtedness, together with late fees, service

charges or liquidated damages (but only if, and to the extent, provided for in

the Sales Agreement) and interest at the rate specified therein) This Guaranty

shall be a guaranty of payment, and not of collection, and the Seller shall not

be required to take any proceedings or exhaust its remedies against the Customer

prior to the exercise of its rights and remedies against the Guarantor, as

guarantor.

The Guarantor hereby agrees to reimburse the Seller for all sums paid to it

by the Customer under the Sales Agreement, which must subsequently be returned

by the Seller to the Customer as a preference or fraudulent transfer under the

Federal Bankruptcy Code, any applicable state law and for any other reason.

Notwithstanding anything else in this Guaranty to the contrary, the

obligation and liability of Guarantor hereunder shall not (i) be effective or

enforceable with respect to any Obligation, liability or claim relating in any

way to consequential, indirect, punitive or exemplary damages of any kind

whatsoever, whether owing by Company or otherwise, and (ii) exceed Fifteen

Million Dollars ($15,000,000) in the aggregate. This Guaranty is a continuing

guaranty and shall remain in full force and effect from August 12, 2002 until at

least March 31, 2005, and shall continue on a monthly basis thereafter, unless

terminated by either party with thirty (30) days written notice to the other

party.

If the Guarantor shall be adjudicated bankrupt under the Federal Bankruptcy

Laws, or if any petition for any relief under any of such laws shall be filed by

or against the Guarantor, or if the Guarantor shall make an assignment for the

benefit of creditors or shall apply for a receiver for all or any part of its

property, or if the Guarantor shall become insolvent or una