These "aircraft tugs" are shortened-wheelbase production trucks that are used to tow fighters, small biz-jets, and aerospace ground equipment (AGE), i.e. air power generators, light carts, large fire extinguisers, LOX and liquid nitrogen tanks and the like. You couldn't actually pull a bomber with one, unless it was a B-24 or something like that; certainly NOT a B-1 or a B-52. Heavy aircraft like that are pulled by very large tugs, about four times the size of a pickup and weighing close to 50K pounds. Clark is one builder of the large tugs.
The smaller tugs are still being manufactured. Here at Tinker AFB, we have several small Jeep CJ tugs (about 25" shorter than a regular CJ) and a few Dodge Cummins tugs. The rear axle is immediately behing the cab on these, and the tire is maybe two inches away from the cab. These are slow-moving vehicles, with gear ratios in the low sevens! GM, Ford, Dodge, and Jeep vehicles are converted, and I've even seen an old Studebaker tug in Tulsa a few years back.
http://cgi.ebay.com/ebaymotors/ws/e...ry=26442&item=45272 99223&rd=1 A photo of a Ford equipment tug.
http://cgi.ebay.com/ebaymotors/ws/e...=4527299191&rd=1&ssPageName=WDVW Another of a Jeep equipment tug.
No, these are not mine.
I've seen a couple of the cabs you are talking about. If I remember right they were built by a coachbuilder and not directly by GM and were used for military use, as firetrucks etc.. I've seen a few of these custom built for COE rod haulers using a couple of cabs and a bunch of doors. I'm not much of an Advance Design truck expert, maybe someone else can jump in and help here. Please take pics when you look at the truck!