EXHIBIT 6 [Letterhead] PERSONAL AND CONFIDENTIAL May 17, 1999 Board of Directors Wyman-Gordan Company 244 Worcester Street North Grafton, MA 01536-8001 Gentlemen: You have requested our opinion as to the fairness from a financial point of view to the holders of the outstanding shares of Common Stock, par value $1.00 per share (the "Shares"), of Wyman-Gordon Company (the "Company") of the $20.00 per Share in cash proposed to be paid by Precision Castparts Corporation ("Buyer") in the Tender Offer and the Merger (as defined below) pursuant to the Agreement and Plan of Merger, dated as of May 17, 1999, among Buyer, WGC Acquisition Corp., a wholly-owned subsidiary of Buyer ("Acquisition Sub"), and the Company (the "Agreement"). The Agreement provides for a tender offer for all of the Shares (the "Tender Offer") pursuant to which Acquisition Sub will pay $20.00 per Share in cash for each Share accepted. The Agreement further provides that following completion of the Tender Offer, Acquisition Sub will be merged into the Company (the "Merger") and each outstanding Share (other than Shares already owned by Acquisition Sub) will be converted into the right to receive $20.00 in cash. Goldman, Sachs & Co., as part of its investment banking business, is continually engaged in the valuation of businesses and their securities in connection with mergers and acquisitions, negotiated underwritings, competitive biddings, secondary distributions of listed and unlisted securities, private placements and valuations for estate, corporate and other purposes. We are familiar with the Company having acted as its financial advisor in connection with, and having participated in certain of the negotiations leading to, the Agreement. We also have provided certain investment banking services to Buyer from time to time, including having acted as managing underwriter of a public offering of $150,000,000 aggregate principal amount of 6 1/8% Senior Notes of Buyer due December 15, 2007 in December 1997, and may provide investment banking services to Buyer and its subsidiaries in the future. Goldman, Sachs & Co. provides a full range of financial advisory and securities services and, in the course of its normal trading activities, may from time to time effect transactions and hold securities, including derivative securities, of the Company or Buyer for its own account and for the accounts of customers. Wyman-Gordon Company May 17, 1999 Page Two In connection with this opinion, we have reviewed, among other things, the Agreement; Annual Reports to Stockholders and Annual Reports on Form 10-K of the Company for the five fiscal years ended May 31, 1998; certain interim reports to stockholders and Quarterly Reports on Form 10-Q of the Company; certain other communications from the Company to its stockholders; and certain internal financial analyses and forecasts for the Company prepared by its management. We also have held discussions with members of the senior management of the Company regarding its past and current business operations, financial condition and future prospects. In addition, we have reviewed the reported price and trading activity for the Shares, compared certain financial and stock market information for the Company with similar information for certain other companies the securities of which are publicly traded, reviewed the financial terms of certain recent business combinations in the aerospace components industry specifically and in other industries generally and performed such other studies and analyses as we considered appropriate. We have relied upon the accuracy and completeness of all of the financial and other information reviewed by us and have assumed such accuracy and completeness for purposes of rendering this opinion. In addition, we have not made an independent evaluation or appraisal of the assets and liabilities of the Company or any of its subsidiaries and we have not been furnished with any such evaluation or appraisal. Our advisory services and the opinion expressed herein are provided for the information and assistance of the Board of Directors of the Company in connection with its consideration of the transaction contemplated by the Agreement and such opinion does not constitute a recommendation as to whether or not any holder of Shares should tender such Shares in connection with such transaction. Based upon and subject to the foregoing and based upon such other matters as we consider relevant, it is our opinion that as of the date hereof the $20.00 per Share in cash to be received by the holders of Shares in the Tender Offer and the Merger is fair from a financial point of view to such holders. Very truly yours, /s/ Goldman, Sachs & Co. - -------------------------------- (GOLDMAN, SACHS & CO.)