44 rear means a Dana 44 rear axle, they are available under some model TJ's. They are much stronger in comparison to the more common Dana 35. The Dana 44 has a 30 spline axle shaft and does not use C-Clips. The Dana 35 has a 27 slpline rear axle and uses C-Clips. Also the diamter of the 44 ring gear is bigger(8.25" vs 7.27"), and the wall thickness on the tubes is thicker.