Don,
I believe they are not interchangeable. 1937-1940 blocks have a single hole for the pump, later 216s have two holes.
Kent


1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix