The Toy surf/4runner has ADD: Automaticly disconecting differentials. If you go into 4H or 4L an electronic switch activates a vacuum pump on the front axle and "connects" the front axle to the drivr shaft. "Dodgy" because there could be problems with the vacuum pump, pump hoses and/or electronics. I will be swopping mine out for manual hubbs as soon as I have the tom.

Ah, there's always more than i understand ;-)

Is it worth changing it though? Am i right in thinking that if it malfunctions all that will happen is you are stuck in 2WD until you get it fixed. Is it bush fixable? I'd guess if its a hose broken it could be, pump gone maybe not. I'm not in the wilds like you but i think i'll stick with the ease of auto changing into 4WD for now, getting upto my ears in mud once when it breaks probably better than every time to get out and switch the hubs! Thats if i understand all this.... which i realy can't say for sure i do :-/

Cheers