The 1.6 and cosworth shells are the same except for the sunroof, some very minor tweaks were done to the shells after they were made, such as drilling a couple of holes and in the case of the rs500 chopping a corner off the battery tray, but that takes all of about 1 minute to replicate both of.

The only other difference is very early shells have a narrower opening for the gearbox at the front of the tunnel and different gearbox mounting points, but the later ones are the same.