All Rangers are 28 spline except for the FX level II. It has a Torsen differential with preload and 31 spline axles. The Explorers have 31 spline rear axle as well. I run a Truetrac in my Ranger/06/4x4/sport and I do 2/3 of my driving on primary and secondary logging roads, North West coast of Vancouver Island. Performs flawlessly on extreme grades, swichbacks and incredible build ups of snow and still has highway manners. Will make your previous clutch pack Trac Loc look like an open diff.