This can be tricky, and dangerous, if your not careful. If its a 4x4, then you'll have to take the transfer case off first to lessen the load. I have never pulled the engine tranny together on a s series truck, I can assume it can be done without too much trouble. If you are pulling the tranny though, you might as well just rebuild the tranny. If its still working alright, just change the clutches, and go through it. Good luck, sounds like you have a lot of work ahead of you.