At 15K it might not be so bad, if only they told more about the machine..
If the rear diff. has been gone through, and the engine is fresh, tracks not to old ect., and the big one, flexators on the bogie wheels... It might not seem so high priced. But with no information regarding service records, replaced components, ect.. it sure seems high, for it's age and what it is..
My bet is they have the information and would likely pass it on to the buyer. It's jut to bad they didn't include what has been done in the for sale add.
Regards, Kirk