The entire G-742 series of trucks (i.e. - M35-style) were designed as replacements for the WWII-era CCKW, drawing on lessons learned from those vehicles as well as advances in automotive engineering and the quest for standardization. At the outset of WWII, automotive specialists with the Quartermaster Corps laid down the criteria for trucks, and when it came to 2 1/2-ton 6x6 dump trucks, specified a shorter bed in order to prevent overloading when loaded with high-density materials.
The Engineers did not like this, because they wanted to be able to transport a full squad of men in the truck, or long timbers, if the truck was not being used to transport loose bulk cargo (i.e. - used as a dump truck). About the same time, responsibility for truck development was transferred from the Quartermaster Corps to the Ordnance Corps.
A compromise was reached, and the CCKW Cargo-Dump was born. This truck had a hinged flap in the the forward portion of the bed which was to be raised when the vehicle was being used as a dump truck, with the cargo to occupy only the area to the rear of the flap, in order to prevent overloading. This reduced the effective capacity of the bed from 3.85 cubic yards to 2.58 cubic yards.
When the G-742 family rolled around, again the designers preferred a shorter dump body, and accordingly the M47 and M59 were created, with 9-foot dump bodies on 142-inch wheelbase chassis, dumping pretty much right at the rear wheels. Once again, the Engineers bemoaned that a squad could not be transported in the truck, and also complaining that the M47 and M59 dump too close to the rear axles.
Along came the 2.5 cubic yard M342 dump truck, with a 11-foot bed, like the M47 and M59 utilizing a subframe to support the bed, but also boasting two lift cylinders. The sideboards of the M342 are lower than that of the M47 and M59, and all three are narrower than a cargo bed and are of more robust construction than that of the cargo trucks.
That said, the dump capacity of all of these trucks is well below that of a commercial dump truck. Table 11 of TM 9-2320-209-10 provides an extensive list of weight/cubic yard limits, noting that both heaping and level full of dirt, the truck will be over the rated cross-country limit, and with sand heaping the truck is even over the on-road limits.
Beyond the obvious operator (and other motorists' safety concerns), overloading any of these trucks risks bending the frame, a failure that tends to happen just behind the cab on un-modified vehicles, and overloading the bed itself. As another poster pointed out, the M35 cargo bed is designed to essentially lay flat on the frame rails. Using at as a dump is going to concentrate the lifting force in smaller area, as well as possibly transferring the direction of the force of the cargo to angles beyond those intended by the designers.
There are vast differences between might, should, has, may, usually and will. The engineers who designed these things worked in the realm of "will," all the other verbs are gambling terms introduced by end users (military and civilian), so as Clint Eastwood says, "do you feel lucky?"
Hope this helps,
David Doyle
www.DavidDoyleBooks.com
