Greg,
Which floor mat will you use with your two-tone interior with Hydra-Matic? Thanks for looking these up. I think you have shown a higher probability that the pins might have been there through 1949. And, I'd guess the pins were not used on Suburbans in any year (but, I'd like to know what the Suburban floor mat "under passenger seat - molded" looked like, especially in 1954 vs earlier years).
It looks like there was no special-colored floor mat in 54/55 for the two-tone burgundy/beige interior?
