Early L322s used the New Venture Gear NV225 transfer box (i.e. petrol models to 2006MY and diesel models to 2007MY, both with 5-speed transmissions). This transfer box was unique to the Range Rover and wasn’t used in any other vehicle.
Once the 6-speed transmission was introduced, all models were fitted with the Magna Steyr DD295 unit. This box was also used in the LR3/LR4 and Sport models, and is still being fitted by Land Rover to this day.
The New Venture box featured a Torsen T-2/Type B centre differential
which is a TORque SENsing device with a torque bias ratio of around 1.85 i.e. it can distribute torque within the range 65/35 front to rear, or rear to front, though of course it’s nominally 50/50 during normal driving conditions. A big advantage of the Torsen arrangement is that it doesn’t rely on one set of wheels to slip before it is activated i.e. it is designed to be a preventative system which does not require a speed differential to function. Unfortunately, as many of us found to our cost, if the front propshaft lets go completely (i.e. spline failure) it can only transmit 1.85 x front propshaft torque to the rear propshaft = 1.85 x zero = a big fat zero.
The Magna box, on the other hand, has an electronically-controlled centre differential which can be locked through engaging (or partially engaging, if torque biasing is required) a multi-plate clutch pack.
Phil
