When I got into the rear main and removed it, all looked fine. No visible place to leak, etc. I DID find, when I removed the cover to the oil pump, that the O-ring was pinched and squished, and I wonder if maybe that was the source of the oil leak?
I replaced the oil pump O-ring per Hucky's recommendation, and tackled the rear main. I had tried to gently get the main seal started the same way I have put in small seals: tap it gently around the edges using a block of wood, but this sucka was to big for that, so I had been thinking....I have had good luck in using the "differential temperature" method of getting tight things to go together. You know, heat the aluminum so that it expands and allows things to go together.... Well, the flipside of that is to cool something to get it to fit into the warmer place....The block was probably 90 F, and I wasn't going to try to heat it up, so.....I soaked the seal in oil overnight, then stuck it into a baggy and threw it into the freezer (missed the photo-op
With some trepidation I placed the cold seal into the hole and could just barely get it to start in....bit it did start. I ever-so-gently went round and round with my wood block and tapped it in. Fits!
Not to anticipate any comments, but, believe me, I am as worried as you are.... I only found out later that there is a special tool for installing the seal at just the correct depth (I eyeballed) and that there is a way to block the crank from moving forward ( was very careful not to push or pull on the crank).
As they say, time will tell...................
Photo is of the cleaned-up case, prior to seal installation