As stated above those have been discussed on here quite a bit and there is also a long thread on Pirate4x4 talking about them.
I won't guarantee this 100% but internet rumors say the axles are something like 20:1 and the NP208 transfer case is locked into 4 low. Even converting the t-case to run in 4 high just the axles alone would be equivalent to a doubler always running low-low with 5.13 axle gears in a normal truck.
Also as stated above there is really no suspension. The axles have a pivot in the middle (ala front axle on farm tractors) with rubber jounce stops on each end, so all they really do is pivot slightly.