Sierra International 18-1989K White 🌡️ Thermostat Service Kit: Optimal Cooling System Maintenance Review

They fit the same as Merc although the color code was reversed. However, due to the placement of the tabs, it is obvious which one to use.

Fits Exactly. I wish they had instructions with them because it's difficult to figure out which way to go and which piece of plastic to use since it's an all in one kit. Finally found a blueprint in the Mercruiser manual.

I bought these gaskets for a 1996 Mercruiser 4.3LX engine. In my case, it's best to use a white plastic thermostat sleeve. Also included is a blue sleeve that is slightly shorter so should fit other models. Installed a new Sierra thermostat and used these gaskets, everything works great.