Nylon nut serts for arm rest screws.

[Lynn]

I think a better term for them is "expansion nuts".

I found these, for GM 1978 and later:

https://www.ebay.com/itm/Arm-Rest-An...tTxqI-&vxp=mtr

They look like they would work, but not sure.

Found these for a Ford.

https://www.ebay.com/itm/15-Ford-Arm...9afO7E&vxp=mtr

And found these, GM nos, with a part number and no picture.

https://www.ebay.com/itm/NOS-Origina...taARQS&vxp=mtr

With all the parts available for first Gen Camaros, I am surprised no one markets these nuts.