if its a 4wd axle it will be a 30 spline only the 2wd and the ifs front end had 27 spline axles going into the carrier, the splines are the grooves that are on the end of the axle shaft that transfer all the touque from the diff to the axle i can probably dig up a picture if you need it i dont know any thing about the 45 or 50 mil hubs for the truetrack