Pinto Car Club of America

hello group i got your attention with the 20 vs 17 .i asking about radiators differences other than size .i have a 77 wagon auto a/c i going to replace a leaking radiator. alot of replacement ones are all 20 with things like a/c auto trans and heavyduty cooling. I'm thinking the 20 is better cause of the extra 3 inch surface.mounting bracket holes look to be in the same holes as the 17on my wagon. ok so what do you think?  chris in ca.