To further qualify that statement from Keithy P38, Sam was running a pneumatically actuated ETC system which he had manufactured and which was far more active, positive and driver adjustable than anything remotely close to a P38 - they dont compare. He also used a different ATB diff to the Ashcroft. I have been in that vehicle and to say it was awesome is a gross understatement.

Can I throw in some considerations - do with then as you please.

The ATB diff - torque biasing, needs to have resistance on the free spinning wheel to bias any torque across to the wheel with more traction. Great for slop and mud etc that you'd come across for general touring etc and I think its a great diff for this as it increases drive. I suspect the target market for these may actually be road/race cars where there is a degree of traction on the tyres at all times rather than 4WD situations. Lifting wheels into the air is the problem. The ETC is meant to apply a braking force to the wheel in the air and then the ETC force is magnified as torque through the ATB diff to the wheel with more traction. If you have an ATB in the rear and in the front then no problem, spin a single rear and a single front, left the ETC and ATB do their stuff and off we go. If you have a locked rear then you need to spin both rears until the ETC activates before the front pulls and thats not necessarily a good situation sometimes, noting off camber situations, steps, rocky gaps and smacking around in ruts/gorges. Although I am twin locked, my panels sometimes let me know when things are not good.

Also, not all ATB's are made the same. How much torque do they bias. Prior to the Ashcroft ATB, there was the Detroit Trutrac and the Quaife. The TT quoted it torque biased by 3:1, Quaife quoted 4:1. Looking at the websites today Ashcroft state 3:1, the now Eaton TT states 3.5:1 and Quaife no longer state thier max biasing ratio but Ashcroft suggest 2:1(Why has this changed??). Perhaps Dave Ashcroft can shed more light on this, but I would have expected if you want a positive biasing ratio through the diff that the TT (Which Sam Overton used) or potentially the Quaife would offer a higher performance unit. Value and accessability may be in the Eaton TT. I do note that Ashcroft sell the Ashcroft ATB, the TT and the Quaife.

To further add to this. I think it is misleading to say that a diff lock will break an axle and an ATB will not break an axle. Mind you I've also heard before that ETC will also break a diff and likewise, 32" tyres are safe but 33" tyres will blow the axles and diffs, and a 4" lift will roll over and to do it the stable way which is 2" spring lift and 2" body lift. You see where I'm going. Any increase in force through an axle is going to increase it chances of breaking. The ATB will probably reduce the shock loading through it however but you still need to show mechanical empathy or it will break.