The numbers on the waterpumps are casting numbers, not part numbers.
After so many thousands of pump bodies cast, the mold is worn out so a new mold is made with its own casting number. There are at least four different casting numbers for the same application waterpump that I have seen. They all "fit" all 235/261 engines 55-62.
Now... a 3757232 pump is from 59-62. It will work just fine on a 57 or 58. But... if one is doing a picky restoration on a 59 with matching numbers then a 57 pump with casting number 3736567 will not do.
It will fit and run just fine, but the "Correct Police" will call you out.
In short... if it looks the same... it is the same.
