Hi,
I would have to think that the rules would hold true for your 63 just like my 65 chevies... In that, as long as you have the rear trim for a sedan be it 2dr or 4dr they should all fit.... Dont take my word for it but I would think this is the most probable answer... For instance, my 65 belair 4dr sedan has a rubber type rear window trim that I had to paint/dye on my own since the reproductions are only in black. I purchased mine through year 1 and they have a tech support line that can answer this question for sure... If any one else knows for sure please feel free to answer.... I hope that helps you out a bit, and good luck...
Ned
65Impala409