Does anyone know how much oil goes in the gearbox and where is the oil filler ? 

Takes 1 liter. The drain is the allen head. If you removed the bolt under the shifter that was a dedent for your shift drum and the stop for the kick start spring! The fill was hard to get to, like under the exhaust header top of the engine. Been decades since I had one.

Is that it ?

No, that's the drain for the crank case. As lineaway said above, its an Allan key about 10 inches behind. 

1000/1200 ml of atf works well.

Edited December 31, 20196 yr by b40rt

Found it on top of engine black cap to fill up thanks guys