There are many diagrams with measurements (some here, and at Team Camaro - use the search function), so unless you find one locally, I would just build my own. I built mine this spring (with brand new steel rectangular tube), had less than $400.00 in it (Unpainted), but it's GREAT, especially if you are doing rails, floor or trunk pans, etc.., as it keeps everything square / level. Good luck on your build.