I used a 2' by 2.5" box tubing ( at least I think thats the right size ) for this car. Welded in on both ends. That could be removed,,,, I guess. But not easily. Biggest advantage to box tubing is they don't follow the contour of the floorplan, thus making it much easier to deal with lines and park brake cables.

Chris , Im pretty sure this car will be at the Nats this summer if you want to see it in person , Car will probably have a for sale sign on it this year.