Yes and no to the question of the wheel base. Here in Germany the wheel base is not making a difference of the basic type, it is for the version of the type. For the Frightliner stuff, means the Mogs for the US Army, they made the serial numbers, even for our European understanding being a 406, a 416 type (didget 3 to 6 of the serial when starting with WDB, else the first three digits). US manuals make the difference for the standard short wheel base was sold as a tractor / working mashine. The other wheel bases were not available in the US exept for the Frightliner versions for the US Army.
Wheel base, gross vehicle weigth, suspension system, engine, transmission variants and so on are coded in the three digits after 406 or 416. for the US the 10th digit, if 17 didgets, should be model year according ISO. In Germany/Europe/RDW (RDW means Rest der Welt exept the US (Rest of the world)) it is the steering position : 1 = left side, 2 = right side, 0 = central steering; thanks to the MB Truck tractor.
This may not be found in the literature. But I have some homologation bussines with Unimog. Thats why I know that the 416 is for the US Army vehicles. The source the the vice president of the Unimog Club who also is the homologation manager of Unimog.
Wolf