I did some research on the Web and was surprised by the huge price difference between the water pums.

Classic Chevrolet Parts stock pump: $99,-
Chevs of the 40s (short shaft): $ 85 + 35 core
Patricks and Langdon (short shaft): about $ 100
Chevy Duty stock $ 49/short shaft $139

and the winner is:

www.Autopart.com stock pump: $ 25,95 + 4 core

I wonder what makes the huge differences?
O.K. the short pumps come with a special pulley but that does not make the almost $100 difference.

To old to die young.