[OrrieG]

Use the link in my signature and look for "restorpacs" or something like that click on one of the 56 or 57 TF truck spec manual. There is a table in there under frame dimensions that gives all the dimensions and gauges of the frame metal. As the trucks get heavier the metal thickness, depth and flange widths increase. There is also a table that lists the different spring sizes and configurations, cab inside dimensions, and lots of other good stuff. I have never heard that the actual frame dimensions are different between gmc and chevy, only how some of the sheet metal and brackets are attached.