I took off the flywheel today and noticed that almost the entire inside of the bellhousing is coated w/ oil. The backside and front of the flywheel are dry. The areas in red have the thickest oily sludge.

Can oil only enter the bellhousing through the rear main seal? The mating surface of the tranny and block look clean, so I don't suspect it leaked from up above by way of leaky cam seals.

Can oil from oil pan leak somehow work its way upwards? I know my oil pan is leaking like a mothertrucker. The flywheel cover had oil both on the outside and inside.

Rear main seal looks fine. Even the dowel on the engine side had oil IN IT.

 

rear main seal

 

Oil leaks down not up. Check high and work your way down. How are the cam seals? How about the distributor o-ring? Its possible its the rear main. It could also be transmission fluid leaking from a bad pinion seal...

 

Pinion doesn't have a seal...

Only seals are the mainshaft and axles. Mainshaft would have oil leaking from the mainshaft, would be on clutch/flywheel. Axles don't leak into the bellhousing clutch side.

 

it looks like the oil plug above the rear main cover.

 

Sorry, i meant mainshaft seal

 

Rear main is my vote.