Allis-Chalmers, Bronco Ammend Merger Terms

Allis-Chalmers Energy Inc. and Bronco Drilling Company, Inc. announced today that they have amended the terms of their previously announced definitive merger agreement providing for the acquisition of Bronco Drilling Company, Inc. by Allis-Chalmers Energy Inc.

The amended agreement provides that at the effective time of the merger, stockholders of Bronco Drilling will receive aggregate merger consideration comprised of (a) $200 million in cash and (b) 16,846,500 shares of Allis-Chalmers common stock. The combined consideration has a value of $18.25 per share of Bronco Drilling common stock based on the closing price of Allis-Chalmers' common stock on May 30, 2008. The number of shares of Allis-Chalmers stock payable as merger consideration is fixed and is not subject to adjustment based on trading value or otherwise. The merger agreement has also been amended such that Allis-Chalmers and Bronco Drilling anticipate that receipt of the stock portion of the merger consideration will be tax-free to Bronco Drilling's stockholders.

Upon completion of the transaction, it is anticipated that Allis-Chalmers' and Bronco Drilling's stockholders will own approximately 68% and 32%, respectively, of the combined company. The boards of directors of both Allis-Chalmers and Bronco Drilling have approved the amended merger agreement. The transaction remains subject to customary conditions, regulatory approvals and approval by the stockholders of each of Allis-Chalmers and Bronco Drilling.