Factory preassembled and ready to rock and roll! When driving ismore important than tinkering, this is the way to keep up with thefast paced world. Please see page-22 in the Hellfire InstructionManual for wire-diagram details. This differential kit includesevery part listed to make your spare time spent driving instead ofassembling: #85500 DIFFERENTIAL CASE#85500 METAL INSERT FOR DIFFERENTIALCASE #86032 BEVEL GEAR(P1x20T/SINTERED METAL) #86099 DIFFCASE WASHER 0.7mm #86520 DIFF SHAFT13x30mm #86521 BEVEL GEAR P1x10T(MODIFIED 86033) #86522 BEVEL GEAR42TOOTH #33406 SHAFT 4x27mm FOR 4BEVEL DIFF #87352 WASHER 4x10x0.15mm#6811 O-RING 6x9.5x1.9(Black) #B085BALL BEARING 8x16x5mm #Z085 FLAT HEAD SCREW M3x15mm (HEX SOCKET)#Z164 HEAVY DUTY GREASE #Z260 PIN 2.5x12mm #Z721 SET SCREW M4x4mm#Z904 ALLEN WRENCH 2.0mm