EXHIBIT 99.1

                  INFORMATION ADDENDUM TO REPORT ON FORM 10-Q
           PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002
           NOT FILED PURSUANT TO THE SECURITIES EXCHANGE ACT OF 1934

Solely for the purpose of Section 906 of the Sarbanes-Oxley Act of 2002, and
solely to the extent this certification may be applicable to this Report on Form
10-Q, the undersigned hereby certify that this report on Form 10-Q of Grant
Prideco, Inc. fully complies with the requirements of section 13(a) or 15(d) of
the Securities Exchange Act of 1934 and that information contained in this
report on Form 10-Q fairly presents, in all material respects, the financial
condition and results of operations of Grant Prideco, Inc.


Date: November 14, 2002                       /s/ Michael McShane
      -----------------------                 ------------------------------
                                              Name: Michael McShane
                                              Title: Chief Executive Officer

                                              /s/ Louis A. Raspino
                                              ------------------------------
                                              Name: Louis A. Raspino
                                              Title: Chief Financial Officer