If you mean the pinion seal, yep. Break the driveline at the rear yoke and undo the big nut holding the yoke on (you'll need a BIG wrench, and maybe someone standing on the brakes in addition to the e-brake being set to keep the diff from turning). Pull the yoke off and pull the old seal with a seal puller or suitable improvised tool (screwdriver). Push the new seal in, making sure the outer edge of the seal aligns with the inner edge of the slight bevel on the inside of the the third member where the yoke goes (so the new seal rides on the smooth machined purpose of the yoke). Replace the yoke and torque the nut to 140ft-lbs.