These frame boxing sets are made to work in conjunction with factory frame motor mounting brackets and crossmembers.  Use this kit if you are NOT using our Cummins conversion mounts. The standard 1/2 kit boxes the frame rails in from the steering box to the transmission cross member, while the extended length option does the whole frame for maximum strength.  We strongly recommend using the full length kits to avoid stress risers. Fabrication and welding are required!  it also comes with machined DOM sleeves for the steering box and grade 8 hardware.