Arrma Front/Rear Transmission Module Set. This optional front or rear transmission module comes preassembled and shimmed with a differential filled with 10,000cSt silicone oil. A straight cut CNC machined ring and pinion gear are used to add extreme durability. Package includes one assembled transmission module intended for the Arrma Bigrock, Granite, Senton and Typhon 3S BLX or Mega or the Kraton 4S and Outcast 4S.