1. The Advance Adapters four-speed transfer case is the proverbial Swiss Army Knife of geardriven torque dividers. While the bulk of the case is similar to the tried-and-true two-speed Atlas, the six-gear planetary underdrive attached to the front of the case makes the unit extremely versatile. It is fitted with a 2.72:1 low and 1:1 high in the forward planetary assembly, and we have the option of shifting from 1:1, 2.0:1. 2.72:1, and 5.4:1.