they are part of the roll cage. safety factor and support for the windshield. if you retain them, you can use any bolt that fits. put some anti-seize on them before tightening. also, cut a rubber gasket from innertube material. eleminate the metal on metal friction.
TREAT EVERY STRESSFUL SITUATION AS A DOG WOULD.
IF YOU CAN'T EAT IT OR PLAY WITH IT,
JUST PEE ON IT AND WALK AWAY.