Eric, You are correct. The 1961-1963 Coupes (body styles 6247 and 6347) have a different part # than the 1963-1964 Coupes (6257 & 6357) in the master parts book. Correspondingly the glass itself has different part #'s across the years which would be expected given the complete redesign of the roof above the beltline between 1962 and 1963.
This is the 2nd time in 2 days I've heard of the convertible door glass channel being sold to someone with the 2 door hard top coupe. Everything about that glass is different! The convertible glass is much shorter top to bottom and about 1/2 to 3/4" longer down the run of the door. And as you would expect, the convertible vent window frames or shorter top to bottom and longer down.
Here is a picture of the convert side glass (missing the rear and top trim, over a 2 door coupe glass. You can clearly see the different in length:
I never got a response about the window channel via link above fitting both convertible and coupe. Here's another older link to a seller that stated they fit 61 to 64 convertible, 61 & 62 Coupe, but not 63/64 Coupe.. .which is more in line from my assumption since the channels are different length in 63 & 64. Here's the other supplier I had on file: https://www.antiquecadillacparts.net/1961-1962-1963-1964-new-cadill...
I have a drivers side 63 Coupe window assembly. Lower channel and top frame are in VG condition.
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