I've changed a bunch of rear main seals, and haven't dropped a transmission yet. It only takes a few thousandths of drop to free up the seal enough to move. I use a couple of pry bars in the ring gear teeth, one on each side of the flywheel, and pry it down a litle, then use the screw-type tool to penetrate the end of the seal and roll it out. Soak the new seal in motor oil, roll it out into a slightly thinner shape than normal, and pull it into place with the chinese handcuff tool. Pack the seal into the slot firmly with a blunt punch, tighten up the mains, and trim the excess seal off flush with the block. Easy!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!