Lego 6 speed gearbox | 3D CAD Model Library | GrabCAD
Ultra Compact 8+N+R Sequential Gearbox - LEGO Technic, Mindstorms, Model Team and Scale Modeling - Eurobricks Forums
Amazon.com: Domani Technic Power Functions Motor Set, Compact Manual Electric 6-Speed Synchronous Gearbox with M Motor, 113 Pieces Building Block Construction Toys Compatible with Lego Technic : Toys & Games
Someone Made a Working Six-Speed Gearbox Out of Legos