Here is a good article that I found and used:
http://www.squarebirds.org/rear_main_seal.htm
I did it twice and found that you should not use sealant between the caps. Offset the two seals so they don't line up with the caps and put a small amount of sealant on the ends. My leak was actually coming from the cam shaft expansion plug. Whoever rebuilt the engine for the previous owner installed it backwards!