GMC 1989 Light Duty Truck Repair Manual page 173

91 / 2-INCH RING GEAR 4B3-11
L O W F L A N K C O N T A C T
D E C R E A S E P IN IO N S H IM
T O E C O N T A C T
IN C R E A S E B A C K L A S H
H E E L C O N T A C T
D E C R E A S E B A C K L A S H
H IG H F A C E C O N T A C T
IN C R E A S E P IN IO N S H IM
F-02018
Figure 24— Gear Tooth Pattern