I am glad you guys are liking the read. I enjoy putting it up and reliving the build.
I have built alot of vehicles over the years, and even helped out on a 31 Essex my brother had built years and years ago. But this build was the most fun. I think as much as anything because it started looking like my vision so quick, and was so simple.
As far as the material goes, I used rectagular tubing in the rear, 3/16 wall. The tubing I used is an EWT type tubing, so you see a seam inside and out. It is known as Welded - Structural Round Steel Tube 1-5/8 OD x .134 wall x 1.357 ID . If you are running NHRA rules and plan to race, you will have to run DOM if you are less than 9 seconds, At least I think that is right, you probably want to check their rules if you are going that route. I think if I would have had some DOM tubing laying around, I would have used it at least on the main rollbar. But I didn't, and I knew the tubing I used would hold up for the weight, and power of the truck.
I think the key to a cage like this is not as much the material, as it the design. Also making it triangulate, or come out square. I cross measured every angle. Everything was checked several times. The advantage is force is carried throughout the entire frame from front to back, and from side to side. The main bar is "X"ed, and the roll bar would connect at 10 points to the main frame. So far the frame has been perfect, no problems, no complaints.