It is not on their website because that is an old rulebook. If you look it still has their class 9 rules, and class 9 isn't allowd to race their anymore. The rules for their equivelent to class 12 are the same as SCORE's rules. If you want the rules on paper, I would call BITD.
I talked with Casey for about an hour right after the Nevada 2000 about a Score Light class and his remarks to me were that there isn't enough 10 cars running BITD to justify a 12 class. At the Nevada 2000, there were only 4 10 cars I think.
I would like to see MDR and Whiplash start a 12 Class (SL) because of the amount of beam cars and A-Arm cars that are starting to run in 10 Class.