Okay, I suspect that my RMS is leaking oil. Not 100% sure yet though
I am going to be converting my 91 to a 5 speed here soon.
The motor is a post 87 motor (1987-1995) 350. I think the casting number is 638 or something around there.
How do I know if it is a 1 piece or 2 piece RMS?
How difficult is it to replace?

Edit: Mortec said this:
14093638...350...87-95...2 or 4...Roller or flat tappet cam, one-piece rear seal

So how hard is it to replace a 1 piece rear main seal?

 

Not as difficult as earlier 2 piece rear main seals. You don't need to take the rear main cap off.

There is an aluminum piece that the seal is contained in bolted to the back of the motor. You take that piece off and replace the seal that's contained in it.
Kinda like the front main seal in the timing cover but bigger.

 

Alright thats not too bad. Can I get a picture of the rear main seal so I have an idea of what to look for?

 

I have an 88 IROC 305 TPI that I suspect is leaking from the rear main. Did you get your's replaced and how easy was it? I know you have to drop the tranny, but does the bell housing have to come off to or can you get in there to remove cover and replace seal with just the tranny out?

thanks,

 

You'll have to take the flywheel or flexplate off to get to the seal, so the bell will have to come off as well.

 

agreed. if you are swapping trannys this will be an easy task. you will have to loosen some oil pan bolts as well in im not mistaken. might as well do a new pan gasket while ur down in there. when i was running a 305, i did the FMS and the pan gasket. i got it all back together, no leaks. then a month later the rear main went out

 

I figured so, but thought I'd ask. Wasn't sure on the pan so this was a good bit of intel. This baby will definately not be pulled apart without all gaskets and seals being replaced. Learned my lesson many moons ago. Its my sons IROC-Z and he needs the experience anyway. Thanks again guys!