Johnny,
I do not know the rules the truck was built to, but I do know it ran at the Southern Invitational in TN this past weekend, and is supposed to be running with FPP this year. It's a 24 valve Cummins that has a P7100 IP. That thing is a real tight fit in there with the 24 valve head.
BCCrawler,
Those trucks look really good. They just need some Dodge bodies, covered in Cummins stickers. I would love to run in a class like that. Any chance you may run at the Worlds or Springs? You otta' try to get that class going. It's the dirt part I don't like. Roughly how much does it cost to put one together? If it's not too much, and you decide to persue getting the class into the NR/CTPA rule book, I'd be more than happy to help sometime.