can anyone please remind me what these are?

They're brackets that screw to the bottom of the front seat, used to attach the sheet metal surround piece. I'm looking for a set if you're willing to sell.

thanks for the info just could not remember putting seats in next week. sorry only one set. if they are the same as a 58 I can look at dick's u pull it for you next week?

I believe they are the same as a '58 Custom or custom 300. If you come across a pair next week I'd appreciate if you could grab them for me.

I have a set of early 57 seat skirts if anyone needs some.  They are different  Check pictures in parts book.  Not sure if they even used those brackets.