4wd same leopard 90 wiring diagram?

Hi,

I have bought an 1980 SAME LEOPARD 90 for my brothers farm, as he needs a 4WD, and farming is not very profitable these days. The tractor is fairly wrecked, so i plan on doing it up in my free time. It needs to be completly re-wired . can anyone send me on the wiring diagram? (and maybe a few details which might help would be great , if possible! ...any help would be very much appreciated)