I decided to go ahead and make my own. I used the same type 3x3 .120 wall tube stock that I used on a Duster project. I didn't want to cut the floors, so I made cuts into the tubes to match the floor. I then welded in the open areas to "box" the tubing. They are welded on 3 sides at the front and rear. I also made my own torque boxes out of 14 guage sheet metal. I suppose that the factory torque boxes were built with thinner guage metal, but since I wasn't sure, I just went with what seemed right. I had to reroute the fuel and brake lines since the frame connectors covered the holes that they passed through. Its not fun welding under a car that is on jackstands! While I am fortunate to be in reasonable physical shape, it is still cramped under there. I popped 3 light bulbs from weld spatter. Dang CFL bulbs....THANKS Al Gore....
I'll post a few pictures soon.