69 barracuda dash to firewall bolts

Forever?? Got size of bolt/screw handy for OP?
Forever ppl have put U Bolts on dash ran bolts up from the bottom this isn't some new idea. Worried about bolt going up a few inches cracking glass. Never heard anyone post up hey I done broke my glass with dash bolt. I guess if bolt is 2 or 3 inches long yeah that could happen.