From the old thread:
"Another sunrise trip to the boat, thistime to pull the water pump (engine, not raw). It is a GM pump, #3839175, which seems pretty standard. The impeller is stamped GM 6269981 MB. The shaft appears to be ss and the impeller bronze with straight fins. Which, I think, makes it a marine, bi-directional pump (right?). There is no apparent physical damage and it spins freely. Other than out of desperate need to do something, I don't think it needs to be replaced, unless I am wrong and it is the wrong pump, in which case I would need some advice as to what to replace it with."