Cool '63. Its a Galaxie, but not a 500, easy to spot by its single side spear. 500's and XL's had a C shaped dual spear. This was the "upscale" post model, as the base Custom 300 model had no side trim, and 500's got you into hardtops.
VIN's on the cowl, on a tab over on the passenger side. As for 5th digit letter codes, R and Q are 8V and 4V 427's, G and B are 6V and 4V 406's, all would have had stick shifts and no power steering or brakes optional. P is hipo 390, Z is hydraulic lifter 390, X is 352, and C is 289, which came out midyear, like the 427's. There were 260's and 223 6's too, but I'm afraid I haven't committed those letters to memory
Check it out some more, could be something special.