1987 300D rear diff gave out
 

I need a rear pumpkin for my 87 300D
Can anyone help me out.
Went around a corner a corner heard a clunk
Then nothing.
Set the parking brake
Climbed under the car with it in neutral and the transmission drive shaft spins freely

More likely your axle snapped...

Look at each axle stub... One must be turning.

Given trans output flanges wear out the splines and lose motion, I wonder when we will see the same thing occur to the diff flange?

I've lost two differentials on my 190DT. The first was probably the victim of a wheel bearing, which failed a few thousand miles later. The second, a used replacement, may have had prior damage. In both cases, the problem began as a rhythmic drubbing noise. No visible problems with axle, driveshaft or couplings. eventually, the diff failed. The first was relatively gentle...thrubbing, a thunk, then nothing. The second was terrifying...the drubbing sound started a few minutes before the axle locked solid, spinning the car around twice on the interstate. Pieces of shrapnel went right through the back of the case. Lucky nobody was hurt, and the car was undamaged. My current differential has more miles than either of the others...at the first weird sound, the car will be on a flatbed.

So you're saying that if I spIn the drive line look for one of the drive shafts to be spending

A failed wheel bearing won't cause a diff to be damaged in an IRS car. ( A car with a solid rear axle that shares diff oil with the wheel bearing can be damaged however. )

Yes... look at the axle shaft on each side... one will be turning.

Very common issue with the greased axles...

Fluids
 

Almost nobody ever changes the fluids out on those, but I change mine. Hopefully mine will continue to last forever.

1991 300d, 205k