tranny.... clutch....?

ok, i've got some good info in another thread. but, i figured i'd bring the question over here where it belongs.

i'm looking at buying an 86 GT. i went and drove it yesterday and it shakes like a bastard when accelerating. pretty sure it's not the motor, cause it revs fine and sounds like it's hitting on all 8. someone suggested that the shaking could be the result of the clutch being bad. (and the owner was very up-front about the car needing a new clutch.) others; the tranny is jacked up. any input or suggestions would be super. i'm just trying to decide whether or not i wanna get the car. don't want it to be more trouble than it's worth. it's only 1000 bucks, so, it's not like i'm dropping my life savings or anything. i just wanna know what possible problems i'd be looking at.

thanks