To remove the pinion flange on a vehicle, start by loosening the wheel lug nuts and raising the rear of the vehicle on jackstands. Disconnect the driveshaft from the differential companion flange and measure the torque required to turn the pinion shaft. Mark the relationship of the pinion flange to the shaft and remove the pinion nut using a flange-holding tool or chain wrench. Withdraw the flange, using a two-jaw puller if necessary, and pry out the old seal. For installation, lubricate the lips of the new seal and tap it into position. Apply RTV sealant to the splines on the pinion shaft and install the pinion flange, aligning the marks made. Install and tighten the old pinion nut, then remove it and install a new pinion nut. Tighten the nut to eliminate pinion shaft end play and measure the rotating torque using an inch-pound torque wrench. Finally, complete the installation in reverse and check the differential lubricant level.