Mine is a 6cyl. It's located beneath the exhaust maifold(don't mess with) and throttle body(again don't mess with).Remove air transfer tube.Disconnect 2 small hoses from black water pipe(metal) andhose at the end of black tube. From driver's side of car pull on black metal tube until it is about 4-6" away from work area. you will need 2-13mm wrenches, 4"and 7or8" and 13mm socket. This is tedious,time consuming and a cussable repair(lower bolt is tough). GM helped here by slotting this hole in thermostat housing,so when reinstalling start the bolt about 1/2 thread before installing housing. Use a GM thermostat only cause you only want to do this once. Good luck.