Is it time to change the rear seal of the tranny? What kind of a job is this to replace?

Sounds like it is, and it is a commonly done operation. I wonder, though, don't you see any evidence of leakage when not wrenching on the flange?

The seal, bushing, and gasket come in a kit, I believe.

The bushing keeps the shaft centered in the seal. It wears and must be pressed out of the governor housing. There's an extraction tool you may see photos of, which can either frustrate you when it doesn't work, or, I guess, make it easy to change the bushing without removing the housing.

A tip I can offer from my own experience: If you pull the housing, and the gasket stays on the transmission in one piece, avoid the hours of scraping just to use that new gasket in the bag by your side. Just re-use the old one with a bit of sealant. Removing the old gasket was by far the most difficult part of the job.

Oh, and don't be surprised at how much ATF comes out when you tap loose that tailshaft housing with the tranny tipped backward.




--
Art Benstein near Baltimore

Why didn't Noah swat those two mosquitoes?