To provide the differential assembly body of a car in which a spider for receiving pinion gears having plural radius direction spokes is accepted in a slot or hole of a surrounding ring shape member.

A differential assembly body 156 used in an auxiliary transmission device or the other mechanism of a car is driven by an input member. A spider 170 arranged on a center position and a pair of side gears, contacted by side are provided. A side gear is provided with plural spokes or shafts and a bevel pinion gear 180 provided on the shaft. The bevel gear 180 is held on the spider 170 by a ring member, which is held on the spider 170 by a cooperative slender slot 160 formed on the ring member and the slot 160 receives the shaft of the spider 170 and a snap ring 168 extending around the circumference of the ring member.