Clean around the nose of the housing and then remove the pinion yoke, pry the old seal out very carefully, clean the inside where the seal sits real good and install the new seal. Make sure there is grease on the inside of the lip on the new seal and put a little, fine coating of wheel bearing grease on the pinion yoke surface the seal rides on and reinstall the pinion yoke, torque the pinion nut to 250 Ft Lbs You might want to put a catch can under the front of the rear end to catch any gear oil that might spill out when you remove the pinion yoke . Check the rear end after your done and add oil as needed throught the filler plug, I like to keep mine down about a 1/2 inch from the edge of the oil filler hole when cold