1996 VDP - Odd rumble at 45-55mph on deceleration

My daily-driver 1996 VDP took a hit from a tree branch in last week’s windstorm - obliterated the driver’s door.
So, while tracking down a replament driver’s door for that car, I found the twin-brother of that car on CL for a song - BOUGHT IT!
It’s a 1996 VDP, with Harmon Karden upgrade sound, heated seats, much nicer clear-coat than my other, peeling, VDP.
I’m happy!
B U T . . .
When motoring along at 60mph, if I simply let off the gas and coast down in speed, there is a rather LOUD RUMBLE from 55 to 45.
The rumble seems to be be body-panel type noise, or interior fitment rumbles. (reminiscent of a 49 Dodge Power Wagon at any speed)

Even if I am going uphill a bit, it still rumbles (but there must be ‘braking’ going on from the engine to the drive wheels).
In any gear, but not in neutral.
Using the brakes does not reduce or increase the rumble.

Rear axle u-joints were freshly greased up.
Flex disks look like they should.
No visible damage to any components.

I’m stumped.
Any thoughts?

I’m no help with your issue, but can relate to the idea of buying another Jaguar when you only need one part! This is how you end up with 15 of them.


Sounds like propshaft drive train universal joints to me.