Racingjunk Forums - Top Stock Class - What exactly is this??

Question for you guys. I have heard reference to an IHRA class called Top Stock. Is there anyone out there that can give me an explanation of exactly what this class is?

There is an NHRA/IHRA class racers forum that has a section devoted to this. But, they don't explain the class either. I've heard that there are weight breaks or maybe just a weight break (single class). They allow an aluminum intake and aftermarket carburator. Also have hear they allow fiberglass hoods. Otherwise they are stock class type cars. Supposed to be heads up racing. I know back in the old days, IHRA had a bunch of oddball classes.

As I said, just interested in getting a breakdown of this class. I've also heard some mention crate motor classes but this is something altogether different. I guess similar to the Super Stock GT class. Allows for different motor combinations with newer body styles?