Mostly metal drivetrain upgrade for Tarmo3 I did it just in order to be able to use larger wheels to ride in mud or show without repairing after each 30 seconds of ride. Also bigger motor has too high torque to use it with plastic diff. I also added cover for servo that helps to hold servo on place without staggering Required parts: 2x Diff HSP 02024 (!!! they are bit different between different selle on Aliexpress, and if you not fit well - just cut out small wall between bearings in diff case and make hole a bit wider with file) - - fits realy well 2x long diff drive wheel HSP 03015 - 4x wheel axile HSP 02168 - 4x 87mm dog bone HSP 06022 - 4x wheel hex - 8x 10x15x4 bearing 8x 5x10x4 bearing