It was getting dark last night, so at a glance these bolts looked like stainless, looking at them this morning they do look to be chrome or zinc plated. Did some searching, they are m10x1.25 38mm partially threaded bolts. In a pinch we got m10x1.25 fully threaded 40mm bolts yesterday at a hardware store. I wont find 38mm, but I'll order 40mm partially threaded bolts of the highest grade I can find to replace them.