6. The Yukon crush-sleeve eliminator kit (the pinion seal is not included) replaces the pinion crush sleeve with shims. In high-stress applications, high torque loads or pinion yoke impacts on the trail can cause the crush sleeve to release the pinion preload with disastrous results. Not a common problem, to be sure, but the shims are a cheap way to add to beef and make setup a bit more precise. The earlier 9.75s had a short crush sleeve, but later ones have a long one, and the second thick spacer shown here is needed to fill the gap.