It can help but only engage on loose surfaces as using it on tarmac will cause transmission windup

Rear locker via the very obvious lever as you say. only use on loose surface as it will make cornering interesting and puts alot of stress on the axle.The front is electrically operated and should be used with great care, thats why it it push button as steering while using it is 1. difficult and 2. could be costly as you may break halfshafts etc. (seel luke harrison for details). The front is only locked while the button is pressed.

rear diff lock Iveco 4x4
 

I have stripped my rear difflock mechanism to get it working. I removed springs and the four bolts and the switch cable( this is probably the electric that you mean Mark) put it in a vice and freed up the lever. When you engage the lever in the cab you have to drive until the axle turns (or spins) enough for the mechanism to be in the correct position to engage. The spring on the pull side sees to this. When you disengage the lever in the cab the return spring disengages the mechanism.
A very simple device.

Graeme

Thanks folks

Press the button, is that the big red button to the left of the steering wheel? Always wondered what that did, though it may be an ejector seat!

Thanks mark

Thats the one !