First, Yes, it's best to remove the side cover to replace the seals, as you really need to remove the shafts from the cover to replace the seals.
Second...hmmm. lemmie tink..I'mma tinkin the rev shaft seal is an o-ring on the shaft itself, which would require removing the tailhousing . I may be tinkin of a different year model tho(earlier Muncie).
If yours does happen to have a metal-clad seal on the outside, fitted into the case around the shaft, then you can change it where it sits, but it may be a bit tricky to get to, considering the location.


Also....on the reverse shaft....there is a pin that holds the shaft into the tailhousing. This pin will also leak where it goes thru the housing. It's always a good idea to clean the area well, and put a dab of sillycone at the top and bottom of the hole where the pin goes. I've seen more leaks at this location than from the actual seal. Adams' Apple2008-02-26 06:18:27

This is one of those repairs that you don't hear about every day and it would be nice to see in pictures and words. Any chance you may give it a shot and share with the rest of us?

Excellent info, thanks..  Got the seals on order and plan to tackle it early next week.  I will take some photo and share the steps I took for sure...

I looked at a few Muncies, and they do appear to have the metal-clad seal for the reverse shaft, so you should be able to change it without removing anything.
You'll need a small, thin screwdriver, or something like a dental pick, to get in between the seal, and the shaft, to pry it out. Once you have to old seal(s) out, be sure to clean the area behind them, so there is no dirt "sealed" on the inside, behind the seal, that will cause the seal to fail.