Never really built a gearbox before but knew the basics of a 2 and 4 speed boxes so i smashed them together and build this kinda small 8 speed gearbox : r/legotechnic
Lego Technic 2 Speed Transmission - Instructables
MoBa Isenheim - Gearbox Update! 2-Speed-Gearbox for light... | Facebook
lego mindstorms gearbox, massive deal UP TO 68% OFF - www.hum.umss.edu.bo
Lego Technic video about Lego 2 Speed Automatic gearbox - worm gear prototype. Includes build instructions.
LEGO Technic 5+R Speed Transmission Gearbox -car truck NXT EV3 - new parts | eBay
Super Easy Building Instructions - 2 Speed Transmission - Lego Technic | Lego technic, Lego, Building instructions