I have a stock 5,000-pound 97 Dodge B2500 conversion turtle top van with the 318 and 4 speed auto overdrive. That van shouldn't (don't do it) be driven over 70 mph, so the overdrive is of no use in that vehicle with that rear. At 80 it can be used, but at 70 it shifts a lot.
My 98 B3500 van 4...