your running 40's on a Dana35 rear axle right? Take the dif cover off and check out your spider gears and ring and pinion. And start looking for a ford 9 inch rear.
lol were did you hear i had 40's? im on stock 27's lol im only getting 31's im gonna watch the junk yards for a wrecked 04+ jeep wrangler rubican or unlimited and take the stock 44s from it.