This is a custom made MAP sensor cover. For the C4 ZR-1 Corvette. The cover is over 1mm thick and made of brass and plated in high temp enamel. I add the year of your ZR-1 and last 3 or 4 of VIN. I’ve sold over 600 and Mercury marine has one on their car at the museum in Wisconsin.
This replaces the thin aluminum plate at the back of the plenum