Dustin, "they" made what ever they wanted, the factory didn't make dumps, the mechanisms were aftermarket setups sold by a number of different companies and could be installed by anyone, including the farmer who wanted it, with any sort of DIY box ... the foot start was an integral part of the original 6 cylinder engine
for some original info about your truck, check out the GM restoration package
from here for your year, the truck could have started as a "cab and chassis" model or a "stake bed", but over it's history almost everything about it has been changed .... and figure out the proper model number, "Loadmaster" doesn't tell you much
Bill
