When the pinion and ring gears are manufactured, the faces of the gear teeth are machined to provide smooth
mating surfaces. The pinion gear and ring gears are always matched to provide a good mesh (Figure 38-24).
Pinion gears and the ring gears should always be installed as a set. Otherwise, the mismatched gear set might
operate noisily. A matched gear set code is etched in each drive pinion and ring gear set.