Anyone have a picture of where/how these mount and which are correct?

Which is correct for 1968 std. interior: 2/seat and round or oval?

Those oval bumpers are a new one to me. It's been a lot of years since I replaced my original, smashed down, seat bumpers but I don't remember the originals being anything different from the repro round one I replaced them with. I do know there were not two per seat back.

I researched some Camaro and other GM late 60's and found the two different seat bumpers. There was a round and oval types, part numbers 4406843 and 7712535 but I could not tell which went with what cars or seat types. (Bucket vs bench? Standard vs custom? Or something else?) Good question.

This is a '68 with custom interior with buckets.

The round ones are correct. I remember there was a discussion about the oval ones way back (2006?) and we determined they were for a totally different car.
Amazing OER just continues to peddle incorrect info.

Actually, OER is correct and Ames is wrong...

This is the driver's seat. I guess the screw shown is the screw that would go through the rubber stopper.

Anyone have or know where to get the 4 prong metal piece underneath the stopper? I'm missing the passenger side.

There is a metal insert in the bumper.

https://www.heartbeatcitycamaro.com/28817/67-68-69-Camaro-Firebird-Chevelle-Nova-Corvair-Bucket-Seat-Back-Bumper-w-embossed-GM-Part%23-4406843/