They weren't prototypes, they were pilot cars The body tubs were assembles in the No. 21 Detroit Pilot assembly line and sent over to Norwood (and a couple to LA) to be final assembled, just like if Fisher built the tub at Norwood and Chevrolet finished them. Some were used for shows, some were used for engineering testing, some were used to prepare the tooling at the plants for the normal model year run. Some, 4 at least, still exist with low VINs, and most have low body tag numbers (like less than 50). The one odd surviving one is the one carrying the VIN100001, it has a body number of 920 for some unknown reason. Best guess is that since it was a show car, and outfitted with a 120V lighting package it had to go back to Norwood and get reconfigured for sale, and it got its original cowl tag replaced at that time to indicate it complied with the Federal codes. But that's a whole nother topic.
