Maybe more than you wanted to know...
Stock classes are designated A/S, B/S, C/S (A/SA, B/SA, C/SA for automatic trans cars) also called A/stock, B/stock, etc. The Highest letter (A) is generally the fastest. Jerry MacNeish runs his 67 Z in E/stock. These cars generally have a stock-appearing body, must run unported factory heads, and the cam lift specs must be factory. My 70 L78 Camaro has a factor of 8.89 so would race in the B/Stock category. More info can be found here at the
NHRA web site.
Super stock classes are SS/A, SS/B, etc (SS/AA for automatic). These care are faster than stock, and again the A class is the fastest. These cars are allowed non-factory hood scoops and generally the rules for these cars are more liberal than for Stock. The most famous SS cars are probably the 1968 Hemi Darts and Barracuda's, they still regularly win this class at NHRA events.
As a rule of thumb, automatic class index is generally half a hundredth slower than the same class with a stick.
Other classes of note are A/MP, B/MP (modified production, I think you will see this class on a lot of motion race cars)and A/FX - factory experimental which was the forerunner of the modern funny cars with altered wheel bases and set back engines ("Gee, that's a funny looking car!").
Here is a cool MP car
Granny Goose II and here is Dick Landy's
"First Funny Car"
