question about a 8 3/4' mopar differential

The gaskets inside the drums from the factory,were white foam. The ones between the backing plates and the flanges were embossed metal. The embossed metal I have always just slammed in there without a care as to this way or that way.
Like Repli says, if your gear oil was in the drums, replace the inner seals,(the ones in the axle tubes) and repack the bearings. The outer seals "may" be fine enough to keep the grease in.If your brake shoes were oiled they are toast, throw them away. If the drums were oiled, they need to be solvent washed, gas-washed,dried, and oven cooked,at more than 250*F,til the stop smoking. Then cooled and gas-washed again.
The gas-wash is very dangerous, so a lot of guys use a generic brake-cleaner instead.More money, less efficient, but waaay safer. Do not use Diesel, or kerosene;these have oils and paraffins in them.