Here is an ad from 1956 for an accessory that looks a lot like the feature introduced by Cadillac in 1954 for some of their models between 1954 - 1956. This was a 'built in' visor-like 2 inch roof overhang that extended across the upper windshield. Although Cadillac is not mentioned in this ad, this is suspiciously Cadillac inspired. Note that the trim advertised was not offered for Cadillac models. Clay/Lexi