I took the LU apart from a 71 johnson electric shift 60hp motor. My question is, before I put it back together do I have to do the shimming and stuff. I was reading in my manual and it has a section about shimming the drive shaft. Cant I just put everything back together in the order I took it apart, or will that not work? If I do have to do some shimming, is it hard, and does it take special tools?