rear main seal install tool
If it's just for expanding the seal to go over the crankshaft, then no.
I had a leaking seal, was sure it was the cover not being centered, but later found it was because the seal had folded over a little on the first attempt at installing, and left a crease in the seal when it went on successfully on the second attempt.
if you support the weight of the cover, the rear seal basiclly centers itself.
i dont see how you can easily change the seal without removing the cover.
btw, i have no idea what the "official GM way" of doing it is... i just know from working on them.
That plastic ring that comes inside the seal, can be used to help stretch the seal over the crank. Just roll a few layers of masking tape around the ring, then put it back inside the seal.
You may have to experiment to find out how many layers you need to get it to go over the crank, but not so many that it's too tight to get the ring to go back inside the seal...
When you put the cover back on the back of the engine, the seal will center itself on the crank and the oil pan will make sure it's not tilted.






