dealbud, if the ONLY reason you are pulling the engine is due to the rear main seal, it is not necessary. There are ways to do it with the engine in place.
If I was pulling the engine, I would leave the tranny in place, due to the length. I would hook the chain, using " L " brackets, to head bolts at opposite front/back corners. Furthermore, if I was going to disassemble the engine, I would probably remove the head.
What car is it in??
Ben
Bookmarks