8.11.7 Door,quarter and rear window glass must be OEM or clear Lexan with a 3mm minimum thickness and securley bolted in place. Windshields must be installed and OEM glass or OEM replacement material (i.e Speedglass) and be free of cracks. Non-glass, replacement windshields must be a minimum 3 1/16" thickness, be adequately mounted, and have supplemental, vertical bracing made of minimum 16 gauge (.0625") aluminum and 3/4" wide, securely mounted down the center of the opening, inside the vehicle.