Running at the right temperature maximizes performance. A failed thermostat can cause an engine to run at outside of its optimum temperature adversely affecting performance and efficiency. The fix can be as simple as replacing the thermostat. Sierra thermostats are engineered to meet manufacturers specifications. This thermostat has a temperature rating of 140 and is designed for use with GM inline 6 cylinder engines (1964—1998) and Chrysler 55hp and 60hp (1977—1984) Force engines with standard cooling systems. Maximize efficiency and performance with a Sierra thermostat. Key Features Thermostat meets or exceeds manufacturer specificationsTemperature rating of 140F Compatible with MerCruiser 120/2.5L (s/n 2324347 & Up) w/cast iron exhaust manifolds, Mercruiser 140-3.0L (s/n 0L340999 & below) and 165 18-3550 Application Guide ApplicationOEM Part NumberChrysler/Force/US MarineF84068-2, F85068-2, F84068-1, F84068GLM13020Mallory9-43020MerCruiser Sterndrive59078B, 59078A1, 59078The Sierra Engine Parts SelectorIn addition to thermostats, we offer a wide variety of other engine parts manufactured by Sierra. To see if we have the part you need, see ourEngine Parts Selector, where you can search by engine make, serial number and model or year of manufacture.