Can someone look up a part number for a water pump?

It seems the castings made before 1977-1978 had 2 web supports cast in between bolt holes. The date code on mine is 1979 so it has only one web support between bolt holes. This is from my 1973 318 V8. This is not identical to the one the car came from the factory with but it will work the same. I'm going to install it and maybe keep an eye out for a correct date coded one in the future. Do I have the facts correct here? Will a casting date coded 1973 have the same part number?