I believe mine are 1" longer than stock now, but anything more than 3/4" longer and you will start to see the teeth of the driveshaft spline start coming out if the rubber cover. That is why I had my driveshaft lengthen about 1", now the teeth of the spline on driveshaft are not showing anymore. Depends on how much lift you have to match the pinion angle at the transfer case. Easiest way is to measure exactly the length from pinion joint to pinion joint on the transfer case top pinion to diff top pinion, and transfer case pinion bottom to diff pinion bottom.