body mounting

[blaylock6502]

Hey guys i have a 74 CJ5 . I bought a used fiberglass tub and have it prepped but trying to find a good way to mount it. I have 2 inch square tubing running from front to back for the first three mounts and a piece of tubing running from front to back the length of the rear part on the rear mount. I am using flat stock on the inside as a washer running the same length of the tubing. The question I have is Im trying to find a way to mount the tubing to the frame. I am a chevrolet technician and I dont know if anyone is familiar with what im talking about but the bolts that come with a hitch for a colorado go inside the frame and have what amounts to a 2 inch piece of flatstock perpendicular to the shaft of the bolt so when the nut is tightened the flat stock cocks sideways inside of the frame and keeps the bolt from turning. That is what I was wanting to use on the frame to tubing but for the life of me cant find anything online. Maybe it is specific to application, but i have to imagine there is something out there that would work. Any input or other ideas is greatly appreciated. And I may just have to weld them although that will be difficult in a 3 foot piece of tubing.