Ive said only that so called "3:1" and "4:1" HL gearboxes have the same gear ratio and Im not described them as the "standard" HL gearboxes /with one gear less/ . But to avoid any confusion Ive deleted my previous post. The descriptions "3:1" or "4:1" HL gearboxes was introduced by suppliers not by me. I dont see difference between them because both have the same amount of gears and shafts - four .The standard HL gearboxes with three shafts was sometimes called by some suppliers "2:1" - I dont know why too.

for example
3:1
http://www.rctank.de/31-PRO-steel-ge...m-/-long-axles
http://www.rctank.de/31-PRO-steel-ge...-/-short-axles

4:1
http://www.rctank.de/41-PRO-steel-ge...-motors/18000t
http://www.rctank.de/NEW-STEEL-LOW-R...RBOXES-TIGER-I