1942 D47J D4400 pony losing oit - into pinion housing

Hi camaroman,
You will be loosing the oil through fhe rear main seal. In the parts book the seal is a 2b6005 which changes to a 5k2595 the info is found in the parts book under Crankshaft for the pony motor.

Regards

Hi replaced that with a new one but I think crank was a little worn. The seal felt like it was positively making contact but maybe I’ll pull it and throw on a speedy sleeve or epoxy and an updated seal.

I do have a lot of blow by probably not helping

Hi CamaroMan, in addition to Daryl's comments, it's good to understand that there are three "chambers": the pony crankcase which as Daryl pointed out, has a crankshaft seal. That seal runs on a ring sandwiched between a shoulder on the crank and the gear. That must also be oil-tight. The second chamber is the one that that gear, the idler, and the pinion driven gear are in. It has its own oil fill/level/drain plugs and relies on that crank seal and the seal on the pinion shaft. Third is the pinion clutch chamber relying on the pinion shaft seal. So, there's really only two places that the oil can leak, and in seeing your description of the pony losing oil and the pinion clutch housing making oil, I'd conclude that both seals are leaking