If you have such concern over the condition of the expensive parts, ie: running gear, and can't check it out pre purchase, maybe you should look else where.I have a feeling the seller would not be amenable to doing that
If some buyer wanted to change my gear oil- on their dime and time, be my guest (I'd be watching and dictating what they use though).
So many Pinzgauers out there, (usually with owner's not following this site), have had little or no maintenance (just ask Scott at EI, or Dennis at Linden Eng. about the numbers of destroyed pinzies they are parting out).
I helped one member of this site do his first transmission oil change on his new rig a couple of years ago. We both wondered what the metal rod fragments were that came out the drain hole. Didn't run or shift funny, so he figured it must have been something some one dropped in by accident. Hmmmm.