Here is a Load'N'Go full size pickup truck tool box.. It slips in and out fully loaded in a matter of minutes with a forklift, or the optional 2000# capacity lifting jacks. You can see more of these at www.fleetwest.net. They fit Ford, Chevy, or Dodge pickups... 3/4 ton capacity or better, plus you leave your tailgate on. No holes drilled.
Or... you can build your own with plywood as Dale Wickell has links at about.com