Rattling Gearbox

I have a 82 mk1 1.1 with a standard 4 speed and my gearbox starts to rattle when i'm driving at 4000 revs and higher. It goes away if I pull the gear leaver further into the gear slot. Could this be a problem with my linkage bushings or something else? Would like to hear your opinions on it. 

Linkage slop, can cause iffy shifting detents, as well as bad motor mounts can bind the links, but If the syncros are bad that can cause a rattle as they are dragging or that you didn't get it in to the proper gear.

I would clean and change all the bushings and links.
I would also check the motor mounts for breakage.