AX5 is considered light duty. AX15 is medium. Pretty sure the AX5 used a bell housing that was internal slave only, not that it can't be changed to external. Also I think the AX5 came in both 21 or 23 spline output shaft so you would have to swap it out if that doesn't match up for you. AX15 is 23 spline. What kind of transfer case do you have, what jeep is it going in?