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  **UNITED STATES SECURITIES AND EXCHANGE COMMISSION****Washington, D.C. 20549****AmendmentNo. 1 to Form 10-Q on**Form 10-Q/A****QUARTERLYREPORT PURSUANT TO SECTION 13 OR 15(**d**) OF THE SECURITIES EXCHANGE ACT OF 1934****For the Quarterly Period Ended September 30, 2005****Commission file number 001-15423****Grant Prideco, Inc.**(Exact name of Registrant as specified in its Charter)   **Delaware** **76-0312499**(State or Other Jurisdiction of (I.R.S. EmployerIncorporation or Organization) Identification No.)   **400 N . Sam Houston Pkwy. East**  **Suite 900**  **Houston, Texas** **77060**(Address of Principal Executive Offices) (Zip Code)**(281) 878-8000**(Registrant’s telephone number, including area code)     Indicate by check mark whether the registrant (1) has filed all reports required to be filedby Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (orfor such shorter period that the registrant was required to file such reports), and (2) has beensubject to such filing requirements for the past 90 days.  Yes  þ     No  o     Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 ofthe Exchange Act)  Yes  o     No  þ     Indicate by check mark whether the registrant is an accelerated filer (as defined in Rule12b-2 of the Exchange Act)  Yes  þ     No  o     Indicate the number of shares outstanding of each of the registrant’s classes of common stock,as of the latest practicable date:   **Title of Each Class** **Outstanding at November 1, 2005**   Common Stock, par value $0.01 per share 128,573,025  
 

**Explanatory NoteThisAmendment No. 1 to the Quarterly Report on Form 10-Q for the quarterlyperiod ended September 30, 2005 is being filed solely to clarifyunder Item 4. *Controls and Procedures* that there were nochanges to Grant Prideco’s internal controls over financialreporting that were identified in connection with the evaluationrequired by Rules 13a-15(d) or 15d-15(d) under the Exchange Actduring the quarter ended September 30, 2005 that has materiallyaffected, or is reasonably likely to materially affect, GrantPrideco’s internal control over financial reporting.Additionally, in connection with the filing of Amendment No. 1 andpursuant to SEC rules, the Company is including as Exhibits to thisAmendment No. 1 certain certifications as of the date of thisAmendment No. 1. Except as described herein, this Amendment No. 1does not amend any other disclosure in the Form 10-Q as originallyfiled and does not reflect events occurring after the original filingof the Form 10-Q.**TABLE OF CONTENTS**
 PART IITEM 4. Controls and Procedures PART IIITEM 6. Exhibits Signature Exhibit IndexCertification of Michael McShaneCertification of Matthew D. FitzgeraldSection 1350 Certification

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**PART I****ITEM 4.*****Controls and Procedures*****Evaluation of Disclosure Controls and Procedures**     We have performed an evaluation under the supervision and with the participation of ourmanagement, including our Chief Executive Officer and Chief Financial Officer, of the effectivenessof our disclosure controls and procedures, as defined in Rules 13a-15(e) and 15d-15(e) under theSecurities Exchange Act of 1934 (the Exchange Act), as of September 30, 2005. Based on thatevaluation, our management, including our Chief Executive Officer and Chief Financial Officer,concluded that, as of the end of the period covered by this report (September 30, 2005), ourdisclosure controls and procedures were effective in providing reasonable assurance thatinformation required to be disclosed by us in the reports filed or submitted by us under theExchange Act is recorded, processed, summarized and reported, within the time periods specified inthe SEC’s rules and forms, and that such information is accumulated and communicated to theCompany’s management, including its Chief Executive Officer and Chief Financial Officer, asappropriate, to allow timely decisions regarding required disclosure.**Update on Internal Control Over Financial Reporting**     Our management assessed the effectiveness of our internal control over financial reporting asof December 31, 2004. In making this assessment, it used the framework entitled “Internal Control —Integrated Framework” set forth by the Committee of Sponsoring Organizations of the TreadwayCommission (COSO). Based on its evaluation of the COSO framework applied to Grant Prideco’sinternal control over financial reporting, and the identification of a material weakness related torevenue recognition controls over documentation of delivery terms requested by the customer andcustomer notification necessary to record revenue prior to customer possession of the product,management concluded that Grant Prideco did not maintain effective internal control over financialreporting as of December 31, 2004.     Inorder to address the material weakness identified as of December 31,2004, management implemented corrective measures during the firstquarter of 2005 including: 1) requiring a checklist to be completedprior to revenue recognition to ensure that documentation of deliveryterms requested by the customer and customer notification necessaryto record revenue prior to customer possession of the product iscomplete and accurate, 2) initiating processes and procedures tobetter document the terms of sales transactions including transactionreview and monitoring activities and 3) reviewing all bill and holdsales transactions during the quarter to ensure that they meet thecriteria for revenue recognition. We believe the corrective actionsdescribed above will provide sufficient controls to remedy theidentified material weakness related to revenue recognition, and willimprove both our disclosure controls and procedures and internalcontrol over financial reporting. Management has completed a majorityof its testing for the 2005 annual evaluation under Section 404 ofthe Sarbanes-Oxley Act of 2002 and is currently evaluating thetesting results; our independent auditors have begun their requiredreviews and testing.     Therewere no changes to Grant Prideco’s internal controls overfinancial reporting that were identified in connection with theevaluation required by Rules 13a-15(d) or 15d-15(d) under theExchange Act during the quarter ended September 30, 2005 that hasmaterially affected, or is reasonably likely to materially affect,Grant Prideco’s internal control over financial reporting.**PART II****ITEM 6. *Exhibits***     (a) Exhibits   31.1 Certification of Michael McShane   31.2 Certification of Matthew D.Fitzgerald   32.1 Section 1350 Certification
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**SIGNATURES**     Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, theregistrant has duly caused this report to be signed on its behalf by the undersigned, thereuntoduly authorized.      GRANT PRIDECO, INC.****