Trust me thats from the mouth of one of the best tuners oop north, loads of gboxs busted under warranty.
The petrol torque may be higher but its at a higher rpm so wont be as destructive.
Thats why diesels wreck boxs on all makes of cars when tuned.
You may notice the gearbox in a manual diesel growling if you are to low an rpm, well that wont happen in an auto for obvious reasons.
4.0 ltr in the d2, 4.6 is range rover and i believe there are differences on the box
Plus the gearboxes always last longer in the v8s as people cant afford to thrash them and the engines pull their liners well before the boxes expire!
Lynall