AC vs Non AC Water Pump comparison

if you break down the build plate on the inner fender here is a code for the radiator support size. The 26" was for A/C equipped cars. I suspect the radiator was preattached to it. that would make it a lot easier to assemble the car on the assembly line. Unlikely there would be an assembly mistake in that case.
That only works on C bodies. All the other car lines are welded. I'm not sure on the process when the radiator support and inner fenders got put on a C body but those items are body color, with no marks on bolt heads, and the radiator is not body color, so I doubt that was the way C bodies were assembled, they only go through paint once.