 Complete the following phrase:  Meanwhile, as the final design developments of these two tank destroyers were underway, the Ordce Department became dissatisfied and by November 1941 had issued an additional specification for a tank destroyer with a 3-inch gun in a rotating turret. Design work began immediately. The 3-inch Gun Motor Carriage T35 combined an early-production M4A2 medium tank hull with the 3-inch gun M7 from the M6 Heavy Tank in a cast, circular, open-topped turret. Using lessons learned from combat reports from the 