To get the drums off, you'll need a 36mm socket (3/4" drive) with a solid breaker bar (no swivel) and a 4 ft stout pipe extension.

Have someone stand on the brakes while removing the nut.

Best to drain the tranny oil first, although you can jack one side of the car up high enough so that oil won't leak out of the axle when you pull the drum.
Use jack stands!

Also a good time to redo the brakes while the drums are off, especially if they are oil-soaked.

There is one oil seal in the bearing cover, plus a couple of O-rings and paper gasket(s).

All the parts (for one wheel) are in kit # 311 598 051X.

Use care installing the O-rings as it is very easy to get them pinched and they will leak for sure!   You can lube them with oil or apply a thin film of silicone sealant; this will help prevent the rings from getting pinched.

Tighten the axle nut to 250 Ft-Lb.
Be sure to refill the tranny with Hypoid oil when done.

There is an exploded pic (from Bentley) of the axle assembly here:

Note:  1964 and earlier cars used a metal "drip plate" instead of the
oil "flinger" or slinger washer.   The drip plate had a tube which
discharged excess oil out through a hole in the drum.