It really depends on how it was driven.
The R380 in my '95 Disco had 265k miles on it when I pulled it out (for things unrelated to the gearbox). It was just starting to get a little worn in the baulk rings. The output shaft had light wear.
On the other hand I've seen 100k gearboxes with heavy wear on the splines.
The transfer case was fine (except for corresponding wear at the input..
Four wheel drive allows you to get stuck
in places even more inaccessible.
62 88 Regular
67 109 6cyl NADA x2
74 Lightweight - The Antichrist
95 DI 5-speed
95 D90 5-speed
97 D1 Automatic