This is a Mack 44,000 pound camelback spring rear axle assembly. This axle set can be used with any of our frame kits, and can be adapted for use with almost any other frame. This bogie has a 54" (.620") axle spread, and can use wheels up to 12.00 x 22. The 6 spoke Mack cast wheel set will work with this axle, but the 14.00 x 24 planetary wheel sets will not fit, as the axle spread is not adequate.