Try mounting the brackets without the bar to see if you can them to line up. If not you may not have the correct brackets. Your bar looks like mine. My mounts do not have the angled part with the hole shown in your pictures. Can't say if that's a GMC/Chevy thing or not. Could try the parts wanted forum to see if another bolter might have the mounts. Also try the "Panels and Burbs" forum because I understand the sway bars were standard on panels/suburbans.
Last edited by Forty9; 10/25/2019 4:22 PM. Reason: More info
