That pump was the same for many years the ones that had the reservoir attached were interchangable with the ones that didn't.
They should be dime a dozen. If they all feel they are special let me know I probably have 10-50 laying around here. Except for your failure they hardly ever do anything wrong but leak. I have seen 3-4 do what your pump did. It has to really wear out. I forget how it does it but its really worn out when it occurs.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician