going to be a lot of opinions expressed. Here's mine.
If you remove the rear wheel, the gears on the bevel box and wheel need grease. This should be done at least every 10k miles if you run darkside and don't have to remove the wheel so often.
imho, the driveshaft to bevel box splines should be looked at while the wheel is off. It only takes a few minutes to pull the bevel box. Don't be surprised that on your first observation that you see a lot of dry brown powder. It is mostly moly as moly is actually a dry lubricant. You can put some more grease on if you like (I usually do). Whatever you do, use a high percentage moly lube, not the 3% stuff that you can get at Wallymart. I use Loctite moly grease (60% or more).