I can probably help you with the housing. I would need to know which one it is. Does it have the dipstick as mentioned above? Does the thermostat have plastic around the central plunger?
The only problem this housing can cause is leaks. Before I would throw away a pump I would build a housing in stainless from the remains of the heavy bottom.
Bosch Master, ASE Master, L1
33 years MB technician