Webb, it's probably a good idea to check the fluid in your diff. Easy to do, and should be checked regularly. I think the manual says to check it every 6000?
"Clunking" is often attributed to UJs, but could be a zillion things. Does the clunking occur only when using the clutch? Do you hear it when the car is moving and in gear?
You can do a quick check of the UJs by reaching under the car with it in gear (and the wheels carefully chocked), grab the propshaft and twist it. If there's any play in the UJs, you need to replace all of them.
This is not a great test, but will let you know if they're really bad. Try the above and let us know what happens.
Good luck!