To techinspector1, thanks much for the info. I'm going to copy your reply in my notes file immediately! The other topic I wasn't going to get into was the leaking pinion seal on the diff, and the slight but noticable play in the rear u-joint (and the klunking). I think the tailshaft seal, the pinion seal, and both u-joints are going to get replaced. In the interim I may try greasing the u-joint, see if it helps, or see if it sprays its grease under the car again.

to pro70z28, I don't think the fluid is coming from the tranny itself, the tail of the tranny seems dry, as does the rubber on the slip-yoke. It all seems to be after the large round disc (after the yoke, before the U-joint). BUT I appreciate your suggestion, and you could be completely right--I don't claim any expertese in this area. I will consider this too, and if money allows, I'll probably replace all I can as said above.

Thank you all for your replies. I'm a novice at this, but I try to at least research things myself before I post too many silly questions on a forum.
Never a problem, always a learning opportunity! (I try to remember that when I'm covered in grease and swearing at my buggy).