It sounds like your buddy got a lemon there, or he really beats on his tranny, or the stealership doesn't know how to rebuild a transmission! When I bought mine (91) a year ago, the previous owner told me that the tranny was rebuilt once and it had a new radiator put in. Other than that the only major work (besides lifting and axle swap) that it needs is a rear main seal... but it also has over 200,000 miles on it... not too shabby!
I say buy one, you will love it. Why do you think we are all here talkin about jeeps?

__________________
91 YJ 4.0 5spd
SOA + 1.5" reverse eye RE springs
D44 LS Rear 4.56 gears
36"x14.5" Parnelli Jones'
Jks discos
Warn XD9000i
Banks SS exhaust
High Steer!
And a bunch of home made stuff!