I do not know if pump has pressed on far enough... is there a spec dimension from back of casting to front of pump pulley face?

The radiator is a stock 1955 from a 1 ton panel

Are 1 ton radiators a different dimension than a standard 1/2 ton model?

Old Truck addict
1950 chevy 1 ton napco
1956 gmc 1 ton dually napco
1954 chevy 3/4 ton napco
1957 gmc civil defense napco panel