The one I have that came out of a '68 Shelby Tail light panel is C4SB-13440-B. The first "4" (after the C) is at a different level, higher, than the rest of the number. The wiring harness has C5SB-3407 on the tag. I can't say if it was replaced before I bought the tail light panel and lights, but I got it as a unit.
Steve