Just found this thread. what a nice build... there must be something with some of these old burbs, I have been fighting a vibration ( or gremlin as I like to call it ) as well and can't seem to make it go away, However, after reading that yours was gone for a short time after replacing the driveline, I guess thats the only logical next step for me. keep posting, I'm definately keeping tuned in to see how this turns out.
here's mine from December
http://67-72chevytrucks.com/vboard/s...d.php?t=375291