Here is the mounting of the steering box. I didn't get anything special for a box. It is from a '92 Chevy 1/2 ton. I did have to make a new pitman arm to that was longer and had the correct ends to connect to the box and my steering linkage. 1/4" plate steel boxed and welded into a strong arm.

 

Here you can see the bead going along the frame holding the mounting plate on. I had to remove a little of the box to allow a nut to be placed on the mounting of it. The threads on the box were really soft and striped out on me.

 

This is where I had to notch the frame to allow the steering shaft clearance. I used 1/4" plate steel bent into shape to allow a smooth surface.