Early 78 without shoulder seat belt holes vs Birdcage Replace

Guys, I need some help. Either my October of 77 built ‘78 has some different mounting holes under the Sail Panel, or someone has done some replacing with early parts. Can anyone shed any light?

surely the upper seat belt retractors would have a nut on the backside of the sheet metal, like the mysterious hole that’s too high shown in the pictures. There’s also signs that I’m missing some parts in here. Anyone know what it is supposed to look like?

One of your options would be to get a copy of the factory assembly manual which is available through some of the aftermarket Corvette parts suppliers. It will have some detailed drawings for each step of the assembly of the entire car. It also calls out the parts with their part number.