How do you change the real axle seals on a 1996 gmc k2500?

If you have a full-floating axle, it's pretty easy. You do have to have one specific tool though - a rear axle nut socket. Loosen axle bolts and lug nuts. Jack up rear end and remove wheel. Put a bucket under the hub to catch oil. Remove bolts and slide axle out. Remove axle nut snap-ring. Remove axle nut with axle nut socket. Pull drum off - make sure parking brake is not on - might have to use rubber mallet. Clean brakes and drum using brake cleaner that is OK to spray directly on shoes. Axle seal is in the brake drum. Knock out the old seal from the outside. Re-grease the bearings - buy new ones if you have the scratch. Tap new seal in place. Slide drum onto spindle. Torque axle nut to 50ft-lbs - back nut off no more than 1/4 turn and install snap ring. Install axle with new gasket. Torque axle nuts to 80ft-lbs. Check rear end oil level and fill if necessary. I recently did this to replace a leaky seal, took me about 2 hours or so - most of the time is taken up in cleaning the oil out of the brake assembly.