An axle assembly serves as a primary structural member for a motor vehicle and comprises an axle tube having a first end and a second end and with an opening located near the first end and a mounting module formed as a unitary extension of the axle tube. At least one steel insert is positioned near the first end, and the steel insert is adapted to be welded to a differential carrier to secure the axle tube to the differential carrier. The axle assembly may also have an axle tube formed unitary with the differential carrier.