I actually mentioned this very subject to my wife on a trip last weekend. Our '94 Caravan was setup like that. You had to turn 'OD' off at freeway speeds. I really wish my RAM was the same because I am thinking my switch will eventually fail because I constantly turn it OFF 'OD' because I drive no faster than 45 mph on my job, and the engine lugs if I don't turn off 'OD' because I have a modified DTT transmission.