Form 425

Filed by Bronco Drilling Company, Inc.
pursuant to Rule 425 under the Securities Act of 1933
and deemed filed pursuant to Rule 14a-12
of the Securities Exchange Act of 1934

Subject Company: Allis-Chalmers Energy, Inc.
Commission File No.: 001-02199

Bronco Drilling Company, Inc. Announces
Fourth Quarter and Fiscal Year 2007 Results

     OKLAHOMA CITY—(BUSINESS WIRE)—March 11, 2008—Bronco Drilling Company, Inc., (Nasdaq/GM:BRNC), announced today financial and operational results for the three months and year ended December 31, 2007.

     Revenues for the fourth quarter of 2007 were $69.0 million compared to $76.3 million for the third quarter of 2007 and $82.5 million for the fourth quarter of 2006. Average operating rigs for the fourth quarter of 2007 were 48 compared to 53 for the previous quarter and 50 for the fourth quarter of 2006. Revenue days for the quarter decreased to 3,250 from 3,739 for the previous quarter and from 4,176 for the fourth quarter of 2006. Utilization for the fourth quarter of 2007 was 73% compared to 76% for the previous quarter and 91% for the fourth quarter of 2006.

     Average daily cash margins for our land drilling fleet for the quarter ended December 31, 2007, were $8,747 compared to $8,373 for the previous quarter and $10,142 for the fourth quarter of 2006. Net income for the fourth quarter of 2007 was $6.4 million (see note below regarding non-recurring charge) compared to $11.1 million for the previous quarter and $16.4 million for the fourth quarter of 2006. The Company generated EBITDA of $24.6 million for the fourth quarter of 2007 compared to $28.3 million for the previous quarter and $38.5 million for the fourth quarter of 2006. Results for the fourth quarter of 2007 were impacted by the movement of the rigs to be contributed or sold to Challenger Limited to our various yards in preparation for mobilization to Libya.

     The Company’s fully diluted earnings per share for the quarter ended December 31, 2007, were $0.25. This number includes a non-recurring charge related to the recognition of sales and use tax on historical capital asset expenditures. This resulted in a cumulative adjustment to depreciation and interest expense. Excluding the non-recurring charge, fully diluted earnings per share would be $0.28. This compares to fully diluted earnings per share of $0.42 for the previous quarter and $0.66 for the fourth quarter of 2006.

     Revenues for the year ended December 31, 2007 were $299.0 million compared to $285.8 million for the year ended 2006. Average operating rigs for 2007 grew to 51 from 45 for the previous year. Revenue days for the year decreased to 14,245 from 15,202 for the previous year. Utilization for the year ended December 31, 2007 was 76% compared to 93% for 2006. Average daily cash margins for 2007 were $8,585 compared to $9,618 for the previous year. Net income for 2007 was $37.6 million compared to $59.8 million for 2006. The Company generated EBITDA of $109.7 million in 2007 compared to $130.0 million for the previous year. The Company’s fully diluted earnings per share for the year ended December 31, 2007, was $1.44 compared to $2.43 for 2006.

     On January 4, 2008, we completed our previously announced acquisition of a 25% equity interest in Challenger Limited in exchange for six drilling rigs and $5.0 million in cash. Challenger is an international provider of contract land drilling and workover services to oil and natural gas companies with its principal operations in Libya. Five of the contributed drilling rigs were from our existing marketed fleet and one was a newly constructed rig. In a separate transaction, we sold to Challenger four additional drilling rigs and ancillary equipment for $12.0 million.

     Three of the ten rigs arrived in Libya in late February. We anticipate all three rigs will be operating by early April. The remaining rigs are scheduled to ship periodically in April and May, and we anticipate that all of the rigs will be operating by the beginning of July.

     About Bronco Drilling

     Bronco Drilling Company, Inc., a publicly held company headquartered in Edmond, Oklahoma, is a provider of contract land drilling services and workover services to oil and natural gas exploration and production companies. Bronco’s common stock is quoted on The Nasdaq Global Market under the symbol “BRNC.” For more information about Bronco Drilling Company, Inc., visit http://www.broncodrill.com.

Bronco Drilling Company, Inc. and Subsidiaries
CONSOLIDATED BALANCE SHEETS
(Amounts in thousands, except share par value)

		December 31,
		2007				2006
ASSETS
CURRENT ASSETS
Cash and cash equivalents		$	5,721			$	10,608
Receivables
Trade and other, net of allowance for doubtful accounts of $1,834 and $400 in 2007 and 2006, respectively			61,499				60,282
Contract drilling in progress			2,128				1,989
Income tax receivable			1,191				—
Current deferred income taxes			775				155
Prepaid expenses			705				338
Total current assets			72,019				73,372
PROPERTY AND EQUIPMENT — AT COST
Drilling rigs and related equipment			510,962				396,499
Transportation, office and other equipment			41,942				29,928
			552,904				426,427
Less accumulated depreciation			86,274				44,505
			466,630				381,922
OTHER ASSETS
Goodwill			23,908				21,280
Restricted cash and deposit			2,745				2,600
Intangibles, net, and other			3,303				3,314
			29,956				27,194
		$	568,605			$	482,488
LIABILITIES AND STOCKHOLDERS’ EQUITY
CURRENT LIABILITIES
Accounts payable		$	16,715			$	19,677
Accrued liabilities			19,280				11,767
Income tax payable			—				3,724
Current maturities of long-term debt			1,256				636
Total current liabilities			37,251				35,804
LONG-TERM DEBT, less current maturities			66,862				64,091
DEFERRED INCOME TAXES			68,063				42,608
COMMITMENTS AND CONTINGENCIES (Note 9)
STOCKHOLDERS’ EQUITY
Common stock, $.01 par value, 100,000 shares authorized; 26,031 and 24,938 shares issued and outstanding at December 31, 2007 and 2006			262				250
Additional paid-in capital			298,195				279,355
Retained earnings			97,972				60,380
Total stockholders’ equity			396,429				339,985
		$	568,605			$	482,488

Bronco Drilling Company, Inc. and Subsidiaries
CONSOLIDATED STATEMENTS OF OPERATIONS
(Amounts in thousands, except per share amounts)

		Years Ended December 31,
		2007				2006				2005
REVENUES
Contract drilling revenues, including 1%, 4% and 3% to related parties			276,088			$	285,828			$	77,885
Well service			22,864				—				—
			298,952				285,828				77,885
EXPENSES
Contract drilling			153,797				139,607				44,695
Well service			14,299				—				—
Depreciation and amortization			44,241				30,335				9,143
General and administrative			22,690				15,709				9,395
			235,027				185,651				63,233
Income from operations			63,925				100,177				14,652
OTHER INCOME (EXPENSE)
Interest expense			(4,762	)			(1,736	)			(1,415	)
Loss from early extinguishment of debt			—				(1,000	)			(2,062	)
Interest income			1,239				164				432
Other			294				284				53
			(3,229	)			(2,288	)			(2,992	)
Income before income taxes			60,696				97,889				11,660
Income tax expense			23,104				38,056				6,529
NET INCOME		$	37,592			$	59,833			$	5,131
Income per common share-Basic		$	1.45			$	2.43			$	0.32
Income per common share-Diluted		$	1.44			$	2.43			$	0.31
Weighted average number of shares outstanding-Basic			25,996				24,585				16,259
Weighted average number of shares outstanding-Diluted			26,101				24,623				16,306
PRO FORMA INFORMATION (unaudited):
Historical income before income taxes										$	11,660
Pro forma provision for income taxes											4,396
Pro forma income										$	7,264
Pro forma income per common share-Basic and Diluted										$	0.45
Weighted average number of shares outstanding-Basic											16,259
Weighted average number of shares outstanding-Diluted											16,306

Bronco Drilling Company Inc.
Quarterly Results
Year Ended December 31, 2007
(Amounts in thousands except per share amounts)

		First				Second				Third				Fourth
		Quarter				Quarter				Quarter				Quarter
2007
Revenues		$	78,981			$	74,720			$	76,286			$	68,965
Income from operations			19,643				14,633				18,648				11,001
Income tax expense			7,101				5,428				7,009				3,566
Net income			11,386				8,714				11,068				6,424
Income per share:
Basic			0.44				0.33				0.43				0.25
Diluted			0.44				0.33				0.42				0.25

     Non-GAAP Financial Measures

     This press release includes a presentation of average daily cash margin and EBITDA which are not financial measures recognized under generally accepted accounting principles, or GAAP. Average daily cash margin is a non-GAAP financial measure equal to net income, the most directly comparable GAAP financial measure, minus well service revenue, plus well service expense, income tax expense, other expense, general and administrative expense and depreciation and amortization, and divided by revenue days for the period. EBITDA is a non-GAAP financial measure equal to net income, the most directly comparable GAAP financial measure, plus interest expense, income tax expense and depreciation and amortization. We have presented average daily cash margin and EBITDA because we use these metrics as an integral part of our internal reporting to measure our performance and to evaluate the performance of our senior management. We consider these metrics to be important indicators of the operational strength of our business. A limitation of these metrics, however, is that they do not reflect the periodic costs of certain capitalized tangible and intangible assets used in generating revenues in our business. Management evaluates the costs of such tangible and intangible assets and the impact of related impairments through other financial measures, such as capital expenditures, investment spending and return on capital. Therefore, we believe that average daily cash margin and EBITDA provide useful information to our investors regarding our performance and overall results of operations. Neither average daily cash margin nor EBITDA is intended to be a performance measure that should be regarded as an alternative to, or more meaningful than, either net income as an indicator of operating performance or to cash flows from operating activities as a measure of liquidity. In addition, neither of these metrics is intended to represent funds available for dividends, reinvestment or other discretionary uses, and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with GAAP. These non-GAAP financial measures may not be comparable to similarly titled measures presented by other companies, and may not be identical to corresponding measures used in our various agreements.

     The following presents a reconciliation of average daily cash margin and EBITDA to net income, the most directly comparable GAAP financial measure (in thousands, except revenue days and average daily cash margin):

		Three Months Ended								Three Months Ended
		December 31,								September 30,
		2007				2006				2007
		(Unaudited)								(Unaudited)
Reconciliation of average daily cash margin to net income:
Net income		$	6,424			$	16,352			$	11,068
Well service revenue			(7,189	)			—				(5,845	)
Well service expense			4,447				—				3,931
Income tax expense			3,566				11,867				7,009
Other expense			1,011				705				571
General and administrative			7,247				3,968				5,353
Depreciation and amortization			12,923				9,459				9,219
Drilling margin			28,429				42,351				31,306
Revenue days			3,250				4,176				3,739
Average daily cash margin		$	8,747			$	10,142			$	8,373

		Year Ended
		December 31,
		2007				2006
Reconciliation of average daily cash margin to net income:
Net income		$	37,592			$	59,833
Well service revenue			(22,864	)			—
Well service expense			14,299				—
Income tax expense			23,104				38,056
Other expense			3,229				2,288
General and administrative			22,690				15,709
Depreciation and amortization			44,241				30,335
Drilling margin			122,291				146,221
Revenue days			14,245				15,202
Average daily cash margin		$	8,585			$	9,618

		Three Months								Three Months
		Ended								Ended
		December 31,								September 30,
		2007				2006				2007
		(Unaudited)								(Unaudited)
Calculation of EBITDA:
Net income		$	6,424			$	16,352			$	11,068
Interest expense			1,690				844				1,009
Income tax expense			3,566				11,867				7,009
Depreciation and amortization			12,923				9,459				9,219
EBITDA		$	24,603			$	38,522			$	28,305

		Year Ended
		December 31,
		2007				2006
Calculation of EBITDA:
Net income		$	37,592			$	59,833
Interest expense			4,762				1,736
Income tax expense			23,104				38,056
Depreciation and amortization			44,241				30,335
EBITDA		$	109,699			$	129,960

     Important Information

     On January 23, 2008, Bronco Drilling Company, Inc. (“Bronco Drilling”) entered into a merger agreement with Allis-Chalmers Energy Inc. (“Allis-Chalmers”), providing for the acquisition of Bronco Drilling by Allis-Chalmers. In connection with the proposed merger, Allis-Chalmers filed a registration statement on Form S-4 (Registration No. 333-149326) with the Securities and Exchange Commission (the “SEC”) on February 20, 2008, which registration statement contains a joint proxy statement/prospectus of both companies. Allis-Chalmers and Bronco Drilling may file other relevant documents concerning the proposed merger, including any amendments to such registration statement. INVESTORS ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC, BECAUSE THEY CONTAIN IMPORTANT INFORMATION REGARDING THE MERGER. Investors and security holders may obtain a free copy of the joint proxy statement/prospectus and the other documents free of charge at the website maintained by the SEC at www.sec.gov.

     The documents filed with the SEC by Allis-Chalmers may be obtained free of charge from Allis-Chalmers’ website at www.alchenergy.com or by calling Allis-Chalmers’ Investor Relations department at (713) 369-0550.

     The documents filed with the SEC by Bronco Drilling may be obtained free of charge from Bronco Drilling’s website at www.broncodrill.com or by calling Bronco Drilling’s Investor Relations department at (405) 242-4444.

     Investors and security holders are urged to read the joint proxy statement/prospectus and the other relevant materials before making any voting or investment decision with respect to the proposed merger.

     Allis-Chalmers and Bronco Drilling and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the respective stockholders of each company in connection with the merger. Information about the directors and executive officers of Allis-Chalmers and their ownership of Allis-Chalmers common stock is set forth in its proxy statement filed with the SEC on April 30, 2007. Information about the directors and executive officers of Bronco Drilling and their ownership of Bronco Drilling common stock is set forth in its proxy statement filed with the SEC on April 30, 2007. Investors may obtain additional information regarding the interests of such participants by reading the joint proxy statement/prospectus for the merger.

     THIS PRESS RELEASE IS NOT AN OFFER TO SELL THE SECURITIES OF ALLIS-CHALMERS AND IT IS NOT SOLICITING AN OFFER TO BUY THESE SECURITIES.

     Cautionary Note Regarding Forward-Looking Statements

     The information in this press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements include, but are not limited to, comments pertaining to estimated contract duration. Such statements are subject to risks, uncertainties and assumptions, including, but not limited to, early termination by the customer pursuant to the contract or otherwise, cancellation or completion of certain contracts or projects earlier than expected, operating hazards and other factors described in Bronco Drilling Company, Inc’s. Annual Report on Form 10-K filed with the SEC on March 8, 2007 and other filings with the SEC, which are available free of charge on the SEC’s website at www.sec.gov. Bronco cautions you that forward-looking statements are not guarantees of future performance and that actual results or developments may differ materially from those projected or implied in these statements.

		CONTACT:		Bob Jarvis
				Investor Relations
				Bronco Drilling Company
				(405) 242-4444 Ext: 102
				bjarvis@broncodrill.com