67 Coronet R/T 4-speed thump from rearend when shifting?

I have a 67 Dodge Coronet R/T 4-speed and am experiencing a THUMP when releasing the clutch fromn first to second and second to third. Anyone
have any idea's on cause. Any info appreciated. I am original owner. Car has 50,683 miles. PM me or e mail moparjack67@sbcglobal.net. THANKS for the add MOPARTS!

Pinion snubber hitting the floor? Do you have an extended snubber?

No the snubber I have is the Original that came with the car.

I have seen later model cars do this when they have a lot of backlash in the rear diff. It is annoying but it didn't affect durability.

Other possibilities are U-joints, trans mount, shocks / bushings, exhaust hangars weak.

Are the rear springs sagging, rear ride height low? That will put the stock pinion snubber close to the floor.

I've had a few 8 3/4 center sections that the cross pin that retains the spider gears had started wearing a slot in the center's hub, one was about a 1/2" from ripping the hub into two pieces.

With the rear end jacked up and the tires off the ground, there was a very noticeable lack of movement between the driveshaft yoke and the tires when rotating by hand and changing rotation direction.

Check the noise out, don't assume everything is OK. Gene