You are right, of course, Grun, they are really cars with truck like bodies on them. As to whether or not they use fiberglass they do use some but most are built the same as the cars, metal bodies. Actually the only part of the cars that come off of the originals are the windshield, top, and back glass. For all intents and purposes the cars are identical. Most use the same chassis, suspension, transmissions, and diferentials. The engines are identical in displacement, ignition and carburator.
These are pseudo "stock" cars and "trucks" built with a formula approved by NASCAR to keep them as equal as possible on the track. Part of the reason they use "old" technology. Granted, that "old" technology has been massaged to the max.
