1987 190D 2.5 ... needs repair or replacement driveshaft!

[bentrod]

Hello, my 1987 190D 2.5 manual trans is - I believe - in need of a new or - somehow - repaired driveshaft.
I got an awful drive line sound.
All the usual suspects are serviced, checked and or replaced:
Rear diff oil, trans oil, motor mounts, center bearing, both flex discs.
What I really am concerned is the universal joint ( U -joint ) has an odd NOTCHY then loose feeling spot at the 12 to 6 and 3 to 9 o"clock positions.
Oddly is it does not have an obvious worn out play in the cross of the U-Joint like other domestic pick up trucks when they are shot.
I'm located in the northeast and I can't find any shops that want to work with the u-joint and or have the tools needed to adapt to a Mercedes-Benz drive shaft for balancing.
I've seen that video on youtube with a Sprinter for dremeling out the stakes and putting in a U-joint but I'm not sold on that at all - plus - the fool can't check that critical balance.
I would appreciate any help at all!