ATD Tools 3310 GM Thermostat Wrench The GM Thermostat Wrench is designed to work on GM 3.1 and 3.4 L V6 engines years 1994 to current; The wrench is a 13mm, 12 point with special bends specifically for GM V6 thermostat housings A common job on these motors is thermostat replacement To do this you must remove the thermostat housing and in these applications the bottom-housing bolt is almost inaccessible without removing other parts - until now GM thermostat wrench with its unique shape and design will allow users to remove and install the housing in a fraction of the time it currently takes The wrench is a 13mm, 12 point with special bends specifically for GM V6 thermostat housings