Depends on how far you want to go. Vulcanized seal for the torque ball. Seal for the opening of the torque tube at the mating of the tube and torque ball. In my picture above of the splined drive shaft there is a seal there. Now, the gear oil in the manual is the same as the rear axle. If some leaks in it will not ruin the rear end like ATF does from leaking Dynaflow transmission. I simply drained the very old nasty gear oil in the rear. Made a gasket and refilled. I did not need to go any further as my axles are not leaking at the outer seals behind the drum brake backing plates.
As a side note, no matter how much sealant used and gaskets cut there will always be a drop of gear oil on the garage floor every now and then.