My cuz restored a 70 dart . everything rebuilt or replaced. He rebuilt the 8 3/4 , new seal new bearings etc. Less than 1000 miles and oil is dripping on brake shoes.
Just wondering how the side axle bearing gets lubricated when there is a seal between bearing and oil supply . i always thought the seal housing hada very small hole in it to oil the bearing , but my memory may be deceiving me and that idea maybe from another brand lol .
End play was set up just right and he shouldn't have had any problems .
Any idea what could be the trouble ? he haven't got the axle removed yet so he can't determine if there is some weird fault .

Bearings need to be packed with wheel bearing grease .

Sounds like you possibly damaged the inner seal or it was installed improperly. It must be driven into the stop in the housing and driven in very straight or it WILL leak. Axle bearings are not lubricated from the rear end lube. The only lubrication that they should be gettin gis from the wheel bearing grease that you packed into the bearings much like the front wheel bearings. If the axle lube is getting past the seal it will wash out the bearing lube and shorten the bearing life and get into the brake area.

Ya did you replace the axle seals in the housing? Did you adjust the axle end play properly?