Rear axle 76 Aspen bearings run in oil or are packed with grease?

Sorry to say *but happy* I have never had to take the axles out on my Dodge, but I now get a mild roar after 30 miles and I don't believe it is the trans (4spd OD) as it keeps making noise without power applied, and in neutral too while coasting and stays relevant to the speed of the car. I just bought a gallon of 75/95 to refill the Differential if need but the oil still feels good when I get a "finger full" and rub it and of course there is no way to tell if gear oil is bad by the smell, it smells awful all the time. Still full from when I got the car in 83. I re-did the front carrier bearing in the tranny and replaced the seal about 8 years ago, the thing leaks and I keep it full or nearly so. Around town I don't hear a noise, SO - I was guessing the problem is the axle and I didn't want to waste the 25 bucks and labor to drain and refill if the bearings don't get the benefit of an oil bath. Any insight in this area would be greatly appreciated.

P.S. if I left out any information that would help answer the oil/grease question - please post or message and I will attempt to rsvp quickly... :dontknow:
Author: compubert