 The nickname 'Jimmy', a phonetical diminutive of GMC, could be applied to both their 6x6 and 6x4 units.After World War II, the M35 series truck, originally developed by REO, became the standard -ton truck.First fielded in the 1950s, the M35 family became one of the most successful and long-lived series of trucks ever deployed by the U.S. military.