I had a similar issue, it ended up being the exhaust pipe, right behind the cat, rubbing on the frame cross member. I moved the hangers up a little and it cleared the cross member.
The u-joint on my driveshaft wore out and I was getting the clunk while stopping/accelerating and a lot of vibration at 35-65mph.
I replaced it with a Tom Woods shaft and been running it for around 4 years with absolutely zero issues. I grease all of the zerk fittings at every oil change and...
