My truck actually went through post race tech when they though I came in 2nd place. They had no issues with the truck except the 1 shock per corner thing lol. Most of the Toyota guys in the 4600 class are running some kinda dual toy cases or crawl box with Dana 300 with no issues, I think the doubler thing only applies to transmissions.
Damn, I love the lack of tube bends on this truck.
I also agree on the crawl box... The rules state "Auxiliary transmissions (e. g. secondary transmissions, under / over- drives, etc.) are not permitted" but at no time has a crawl box been identified as an "Auxillary transmission" as far as I can recall. Yeah, it's an "Auxillary transfer case", but that isn't outlawed. And in racing, if it's not specifically illegal then it's legal enough to run. :D