Please feel free to correct me if I'm wrong, but isn't the bed held down by carriage bolts located in offset washers?
How do you plan on spinning the carriage bolts (which normally have the square shoulder on them) in the washer without moving the bed boards around?
As starkweather mentioned above, you may want to drill through the top and bottom of the frame and add his 'crush sleeves' (just use 1/2" pipe cut to fit inside the frame) with much longer bolts so you can easily tighten down the bed.
I didn't box the frame of my '59 3800, but I did add an additional channel that fit within the original frame (see pics here:
http://rides.webshots.com/album/561655740knjkhx ). This way, I only need to lengthen the bolts I need by 1/4".
Lane
