I think my U-joints are shot

[hehhehmule]

I agree with Jerry, try and twist your driveshaft and observe anything unusual. You might also put it in gear and push on it, alot of times even in drive they'll move some and thunk if the u's are bad. I once thought I had a joint going bad and it turned out to be a plug wire off causing my vibration, just a thought. Good luck. BTW I too have a 67 fastback Jerry, it's an S code GTA.