[Stuart]

Nicely done! They're officially called a porch, for some reason. That must be from a Catalina/Ventura with a bench seat - there were actually four different part numbers for 1961 (I imagine 1961-1964 were similar):

540317 Catalina and Ventura with bucket seats
540121 Catalina and Ventura with bench seats
540261 Star Chief and Bonneville with bucket seats
540227 Star Chief and Bonneville with bench seats

Catalinas and Venturas have a smaller transmission hump than the Star Chiefs and Bonnevilles, and the shifter in bucket seat cars is located a little differently than in bench seat cars (I believe the bucket seat porches have a square hole instead of a round hole, as well.)

This is the porch out of my 1961 Bonneville, along with a fiberglass copy I made:

By the way, shouldnt 1961 be included in '62-66 big cars??? Most everything is the same between '61-63, no comparisons to '60 & older.

That's a long standing question around here, no one seems to know why.