Made of compatible steel for attachment to 4.00" tube with 1" of engagement onto the axle tube. Includes outboard oil seal (p/n FRR-014). Sold each. Mounting holes are made to match the 2005 - 2010 F350 unit hub. Bolts not included, but must be at least 1-7/8" long. 

To use, cut the OEM housing ends off and weld the hub cup onto the axle tube. Then, bolt the unit hub on and install axles. 

Installation - Service instructions can be found on Service Bulletin #0104