you folks need to remember that GM was big on using what was on hand that worked, and that the various assembly plants might well have not had what was "spec", but did have "mismatched" leftovers, the primary changes were size to fit in the space [and prolly cheaper to make], and the mounting bracket to allow the 'trumpet' to aim at the louvers in the core support - waste not, want not
for a good instance, the 57-59 panel truck
rear license light cover was identical to the
1939 car cover, including the unobtainium glass thimble inside - they must have had leftovers ... who'd a thunk
Bill
