The rear end if your '95 GMC is what transfers the power from the transmission to the rear wheels. When this part begins to go bad, it is best to repair or replace it before it completely stops working and leaves you stranded. There are a few telltale signs of a rear end going bad. Sometimes you can see the parts going bad and sometimes you only need to listen for the bad components.
Drive your '95 GMC and listen for telltale signs of a faulty rear end. These sounds are a low humming noise or a grinding sound from the rear of the vehicle.
Jack up the rear of the truck and secure it with jack stands.
Run the vehicle in gear so the wheels spin. Use the stethoscope to listen for noises from inside the rear end. This is done by holding the stethoscope to the main pumpkin of the rear end.
Check the rear end fluid level by opening the "Check & Fill" hole, located a little over halfway up the rear end cover, and sticking your finger in the hole. The fluid should be just below the hole. Fill the fluid and recheck if it is low.
Remove the rear differential cover by removing the bolt around the cover and prying the cover off. The number of bolts may vary depending on the rear end size. If you have an 8.5 inch pinion gear on your '95 GMC, it will have 10 bolts. It will have 14 bolts if you have the 10.5 inch pinion gear.
Check the magnet on the cover. There will always be some small metal splinters. You are looking for large chunks of metal. Large chucks of metal mean that something is coming apart internally.
Check the gears inside the rear end for excessive looseness or large chunks of metal missing. This is the most direct sign of internal rear end damage.
