Finally got around to installing my seatbelts/Harness, I drilled 1 inch holes in the roll cage (2009 sq. tube) and used a piece of oak for a drill guide. I used 1" DOM tubing with .180 wall thickness. The harnesses were out of my race car, so I put them to use on the Prowler. I cut the tubing 1 inch longer than the spread between the uprights, the bar slides into the holes I drilled, then I center the bar. This could be a total bolt in using set screw collars, and attaching to the inner uprights. I plan on welding mine in.