It's interesting to note that they're "upgrading" from the VX to the new D-Max with the 3.0L turbo diesel, which is what's been run in the Dakar.

I did find this of note in reference to the Aisin 5-speed used in their VX...
The gearbox is a specially developed square cut five-speed manual transmission, based upon the original ISUZU housing and transfer case. Although modified (as allowed under the rules) from the standard components, many of the improvements that have been learnt over the GRT teams ten year desert racing history. Many have been incorporated back into the ISUZU production vehicle units produced by the factory.