Here's a shot from Englishtown of Bill "Grumpy" Jenkins and "Dyno" Don Nicholson in their match race pro stocks, the forerunner of today's Pro Modified and, to an extent, Pro Stock.

Big inch engines, lots of fiberglass, and no side windows made this style of racing popular with the gas and carb set as they were way lighter and faster than the small block cars they were currently running in national event competition. Nitrous showed up on the scene a short time later and voila... Pro Modified.