1971 GMC C2500 Special Camper....

[SkeksisNV]

I am curious what this truck originally came with. The plate in the glove box shows this truck as a Z81 Special Camper. I am trying to figure out what made it special versus the other trucks of its era. It lists as having a LS9 350 Engine and a M49 Turbo-Hydromatic. Doesn't state which one. I suspect it came with the TH400, but there is a TH350 in there now. Doesn't list what gear it came with in the rear either. Looks like a Dana 44 axle. 3/4 ton 2WD pickup. I have an 1980 GMC 1/2 2WD that is a Sierra Grande, came with two tanks and looks like there is provisions for another battery for the truck. So I can see extra options that may have been made available to the truck with the badge it carries but I am not seeing it. Anyone have any ideas what these codes mean and what makes it a Special Camper?