Yeah, if it were me and i had the Tcase sitting on the work bench to replace the front seal, i'd rebuild it in a heart beat.
Especially if its got mucho miles on it or has seen a lot of wheeling in the past. A no brain'er in my book.

 

the output shaft seal on my tcase leaked. i discovered the vent was clogged. made that right and no more leaks. that was roughly 80k miles ago.

 

That's the kind of stuff you find when pokin your noggin under the Jeep instead of going all out and rebuilding a transfer case.