WALTHAM, Mass., May 12 -- Thermo Instrument Systems Inc. will sell its wholly owned subsidiary Spectra Precision to Trimble Navigation Ltd. Under the terms of the agreement Thermo will receive a cash payment of $200 million and an additional $80 million in seller-debt financing. Thermo Instrument is a Thermo Electron company. Spectra Precision, which we acquired in February 1999 as part of Spectra-Physics AB, provides the construction, surveying, and heavy machine industries with precision positioning equipment, which is outside our renewed focus on measurement and detection instrumentation, commented Earl R. Lewis, president and chief executive officer of Thermo Instrument Systems. Trimble is a recognized worldwide leader in the development of global positioning system technologies and will be better able to exploit the GPS capabilities of Spectra Precision'sinstruments. This divestiture is a win-win situation for all parties involved. The deal, which is subject to regulatory and financial approval, is expected to be finalized by the end of the second quarter.