As I move through my 63 I notice red colored primer pretty much everywhere...floors ,firewall, cowl, trunk, doors.....inners and outers. Is this something GM did? Can anybody chime in with thier experience? Mostly a curiosity factor. Was red a factory undercoat ? Kinda looks like the old laquer primers . There is no evidence that this car has ever been apart but is has had a complete repaint back in the 60's or 70's I'd say.A pic for you with the TTO's after a bunch of elbow grease.
The primer is Red Oxide Primer and that was what GM used in the early years in Canada before applying an enamel top coat. US built cars used lacquer.
Al