4 WHEEL DRIVE. type B. A Housing separate from the Differential Housing to which the Differential Carrier is mounted to. Differential. Part included in Differential Carrier. The Housing of a Differential that holds the gears, pinions, Differential case, etc. Type A = Carrier Retainer Tab At Lower Left. Type B = Carrier Retainer Tab At Upper Left. SUB - Assembly, DI. Axle. CASE. Included with: Differential Carrier, Order by description Differential Carrier.