This video shows how we build our axles straight.
The jig that the housing sits in does not clamp the housing down and hold it straight, it is a tool for adding preload and holding it in place to work on. The welding on each of our housings is different and each housing needs their own preload. For example; our Ford 9″ axle requires more preload due to the fact that when the face plate is welded to the axle tube there are two long weld beads on one side of the tubing causing it to warp more. Other housings like the Sixty9 and the Sold 14 Bolt have a bent faceplate which makes the weld go around the tube making the tube warp less.
Solid 14 Bolt Housing