Amazon.com: LEGO Technic COMPLETE GEARBOX ASSEMBLY 2 x 4 x 3 1/3 Trans-Clear Wormbox gear motor REDUCER block Mindstorms robotics ev3 NXT transparent robot building power functions part 6588 : Toys & Games
Compact 3 Speed Automatic CVT Gearbox | MOCHUB
6 Lego Gearboxes | from Useful to Useless - YouTube
Building & Testing Lego 5-Speed Gearbox - YouTube
LEGO Technic 5+R Speed Transmission Gearbox -car truck NXT EV3 - new parts | eBay
WIP] D-N-R-P + 4-Speed gearbox - LEGO Technic, Mindstorms, Model Team and Scale Modeling - Eurobricks Forums
LEGO MOC 5-Speed + Reverse Gearbox by 1plaintext | Rebrickable - Build with LEGO