6. Not all Sterling pinions are created equal. Three styles have been used over the years. The early gearsets (right) used short splines on the pinion; the late gearsets (left) use a thinner pinion bearing. Don’t mix and match bearings and pinions between generations! They fit but will not function properly. Most aftermarket gearsets, like our 5.13s from Sierra, use the second-generation gears and bearings.