I work for Miller Technology. We base our build on the HZJ79L cab and chassis (old school 1HZ straight 6 mechanical injection diesel coupled to the R151F 5 speed manual transmission, left hand drive). We buy them directly from Toyota and they are imported from Japan.

We also have a battery powered electric conversion kit which really makes them a beast with the instantaneous torque for climbing and regenerative braking which is awesome for down slope navigation.