what's the SPD?
what's the CONTROL # on the IBM card?

I've heard of butchered radio holes on '66 b-bodies before, maybe it was typical on Lynch Rd. cars? I'd start a thread asking: Who has a '66 Lynch Rd. car with a "hack-job" antennae installation?

a lot can happen in 50+ years, but if factory - I wonder if the black sealer wasn't due to the car failing the water test? shruggy all original dated glass? maybe the glass & taillights were broken early in the car's life, how much history do you have on the car?
taillights could've been changed or a mistake, but there shouldn't be any 2-door hardtops with Belvedere I taillights at the factory.

is there something that indicates "Special Order"? usually cars were simply "Ordered" by a dealership or an individual and a "Special Order" was reserved for cars that had something that wasn't a listed OPTION.

an additional OPTION on the car would be the rear axle (3.54:1 DANA60 axle package) - it was a "mandatory OPTION" and had to be paid for