Info - Thermostat Design Change

There may be some confusion as to the correct thermostat application for the above mentioned vehicles when ordering a replacement part due to a design change for the 1999 and 2000 MY vehicles. The design change will affect service replacements of previous 90 degree V6 engines.

The new design will not fit previous 90 degree V6 engines due to a change in the position of the pintle and a different shape of the upper thermostat assembly. Refer to the following figure for identification of the current thermostat.

Important: Noticeable offset of the pintle position.

Parts are currently available from GMSPO. The following table contains: part numbers for the thermostats, the type of housing, whether it uses a gasket or O-ring, and their respective part numbers. The information is listed by year, then engine RPO code. Use the table to order the correct replacement thermostats.