The F9 housing includes our fabricated housing center that features a 3/16" thick Hi-Form 50 steel body, a 3/8" thick Hi-Form 50 steel 3rd. member mounting face (that is notched for use with 10" ring gears), and 3.5" x .250" wall tubes installed. Housing is custom built to your overall width and pinion offset specs. (up to 66" wide - additional width at extra cost). Unique to this design, the first bend in the fabricated housing center is centered with the center line of the axle tube. This allows the bend to be the point of lowest ground clearance, and the flats on the housing to provide maximum ground clearance at up to 20 degrees of pinion angle! Another unique feature are the welded in bulkheads inside the housing center that tie the face, the body, and the inner ends of the tubes all together. We machine a flat on one side of the inner end of the tube which allows it to key into the inner bulkhead before welding. Arguably the strongest fabricated housing design to ever hit the market! Sold each.