I'm in-the-middle of a '66 AMT Mustang chassis-swap project right now, and I can tell you that I originally thought the AMT/Ertl/Round-2 1968 Shelby Mustang GT500 kit's chassis would be a quick-n-easy drop-in replacement, but it's more challenging than I originally thought. Had to add rear wheel wells, cut-out a section of the center of the chassis and replace it, fabricate-in the rear portion of the driveshaft tunnel, add a new transmission-mount brace and I'm still in the process of getting the firewall and chassis to mate to each other properly. I expected a few hours of work, but that's increased to 20+ hours and I'm not done yet.