I picked the shoulder bolt up today from Fastenal. Worked perfectly. I ending up having to pay another $8 in shipping so all together the replacement bolt cost just under $20.
I put a little anti-seize on the shoulder that works as the axle and I put a dap of red loctite on the threads.
Fastenal Part #74118
1/2" shoulder x 2" long shoulder x 3/8"-16 stainless steel socket shoulder bolt