Saginaw was a division of GM for decades until they were spun off with several others divisions into Delphi. Chrysler bought the pumps and adapted them to their applications because they are a good pump.
Mostly Saginaw pumps didn't show up on LA engines until 1969. Because the aluminum water pump came along in 1970, that makes the brackets a one year deal. Original stuff is out there, but not everywhere. So, if you have one in your shed, you could rebuild it and use it. Or call Peter and get everything brand new.
