NASCAR Racing: nascar - stock?, nascar race car, nascar circuit

Question
the name used to mean just that, stock car. I wonder now just how many parts on a nascar race car OR truck can be had at a dealer? exactly how much, if any, of a car built for the nascar circuit are required to be dealer shelf items? the official nascar site blew this question off, completely, which tells me that a ford is not a ford and a chevy is not a chevy. nor is a dodge a dodge.
many of the *bodies* at least look like a front wheel drive production car.
SO, what is the truth about these cars and trucks? just how much is actually available at a dealer? made to fit the cars that nascar racers represent.

Answer
Hey Tom Reeves,

It used to be that the drivers would buy them off of the showroom floor, drive them to the track, race them at the track, then drive it home.

However NASCAR has gotten away from the roots of racing, a major issue to fans everywhere.

All parts of the car are custom made at the race shops themselves. The manufacturer only sends the templates for the car by themselves, so that is why the car at least looks like something from the production cars made. Nothing is stock, it is all custom made.

Hope I helped,
Coy Jordan