This goes in the end of the crank. It's the bushing that the transmission shaft goes into and keeps the transmission shaft centered. There are two different sizes and styles of this. Make sure you get the right one. This one has a 5/8" OD and should fit all 948 and 1098 engines. It will also fit the early 1275. The later 1275 has a needle bearing here that has an OD of 3/4". That can be found here.