I have a model 803
After that is a dash 1266, I know the 12 is for 12th series but what is the 66 for?
The crack around the bushing has been there for quite some time, its really rusted.

Thank's for the information it was very helpful, I thought the radiator would have to be pulled, did not want to do that. I got this car from my wife's grandfather when he died & unfortunately all the info on this car is with him. Now that I have the pump off I can see that the casting is cracked around the packing nut/threaded bushing. Any suggestions who I should go to for a new one? Gould Rebuilders?

My water pump does not look the same as what is in the 1935-1941 parts list book. It looks like the pump is inside the engine block. The threaded bushing that the fan shaft goes through is stripped, it would be helpful to see a diagram of the engine so I can tell how big a job it is to replace the threaded bushing.