My Update:
My dealer felt they could get the hose fabricated locally from a trusted source for a reasonable price -- half of the list of the unavailable part. We did this and the new hose made a funky noise when the car was under power. A surging thrumming droning which could be felt when holding the new hose. They swapped in another customer's old hose -- from a 4Matic -- and the noise was gone. They have worked with MB specification tech reps and found the 4Matic spec hose should fit well (I think hose is just a bit longer), and the part is available. It is en route to the shop now. I will update once complete.

__________________
David
1986 300E Anthracite + ECodes + MB Mileage Award