You might recognize this Silverado 1500 from a Fantastic Four article in 2007. This truck was our first GMT-900 to go under the knife, and we really loved the look we got from the Pro Comp lift, wheels, and tires. The JBA headers and exhaust, combined with an AEM intake, boosted power across the rpm range. And, it also gave the truck a couple hundred rpm in the top end before it began to fall off. But even with an extra 25 hp and 23 lb-ft of torque, the truck still was not quite as peppy as it was with its original wheels and tires.
One year later and the added mass of the 35-inch tires was starting to show by way of some rear-end noise. We decided to do what we probably should have done when we first lifted the truck: add new gears. We called Off Road Warehouse in San Diego, to get the truck on a lift and into some new 4.56:1 gears and a Mag-Hytec diff cover. We also decided it was time to correct the speedometer, which we took upon ourselves. When we first lifted the truck, there weren't any programmers available, but now Hypertech has a solution. Check out how we tuned the truck, solved our speedometer issues, and how Bill "Thunder" Hulls, along with the guys at Off Road Warehouse, resuscitated our Silverado.
Step one was putting the truck on the lift, removing the wheels, and disconnecting the driveline. When the cover was opened, the fluid that came out was in good shape, and the wear on the ring gear was normal. Nothing pointed to the source of the noise. In this shot, you can see the G80 locker in the differential. | 
After removing the set screw, the locking pin was removed. | 
That enabled Bill to push each axle in and remove the C-clips. The C-clips retain the axle in the housing, so if the axle breaks, it can't walk out and take the wheel with it. |