Re: Do I have a 1 or 2 piece rear main seal?
If it's an 86 it'll have a 2 piece main seal (late), but it doesn't matter as they're interchangeable, I'm pretty sure you'll only be able to find a gasket set with a 2 piece main seal, as the 1 piece has become obsolete.
You may be able to get (a) a rope type seal - 1 piece
(b) a rubber type seal - 2 piece
The mains cap that holds the seal has a spike in it that sticks into the rope type seal to stop it spinning with the crank , if using a rubber seal (which is probably the only one u can get) youv'e gotta take this spike out so it doesn't puncture the rubber. You just tap it out with a punch, grind the spiky bit off, and knock the rest (dowel) back into the cap to fill the hole. That's what I did to my 351W years ago with no probs.