[njk53]

That's a really good question. The rear suspensions on the Chevrolet, Ford, and Chrysler factory racers are nowhere near stock configuration, which in my opinion these cars should be using the stock suspensions with the same approved modifications the older cars are allowed. Are the older stockers allowed to use the same technology as the factory built cars? I think not. Also, the newer designed engines have features which allow them to make more horspower and torque per cubic inch than the older engine designs. One item that comes to mind is a roller cam.