There are two possible ways to add proper studs to the knuckles. Our knuckle threads were in good condition so we used threaded studs. The knuckles need to be removed from the axle. The backside of the holes need to be spotfaced for both methods. We used a drill press and a McMaster-Carr counterbore and pilot (PN 3015A28 and PN 3103A29). If the threads on your knuckles are shot, you'll need to drill the holes out to 3/8 and use a 3/8 pilot (PN 3103A3) on the counterbore bit.