The Toyota Pickup is your "Hi-Lux".  So you are using the gear reduction part of the Hi-Lux transfer case between your exsisting transfer case and you transmition to have high range, low range and super low range for serious low geared crawling.

This kind of gear reduction is really astonishing and awesome if you do any kind of 4WD recreation beyond mud racing. It's even kind of handy on work trucks.  You should probably buy it...