How many D-max's have been on their side or lid at the track though? And of those how many sustained bad enough damage to hurt anyone inside (aside from what a roll-bar couldn't help anyways)? I can see unibody cars needing a roll cage, because they are more prone to roll over without the weight of a frame lowering the center of gravity and they are more like to crush in around someone than a full frame truck with a roomy cabin. The rules shouldn't be made any stricter for trucks than they are for cars.