A great deal of trial-and-error goes into building and dialing-in a fresh 8.8. Our Detroit Locker requires side shims before it can be final-installed. Determining correct shim sizes (thickness) takes a while because the locker must be installed and removed several times. However, nailing the perfect shim combination allows Chris to determine the amount of backlash and preload is necessary to absorb the carrier's side-to-side movement on the ring gear. A good, tight fit in the housing is important for any differential.