The 700R4 is a four speed transmission......the turbo 350 is a three speed trans. The 4th gear in the 700R4 is an OverDrive gear, so it will lower the engine rpm's when in OD. I would think that a "Dually" rear end is going to have a lower gear set in it than the Explorer rear end......therefore, making the situation worse, causing the engine rpm's to go even higher at 60mph.
