Based on a fair number of unmolested examples where it appears as though the original running boards have never been removed, the general rule of assembly was applied. That is that the bolt or screw goes with the part being attached. In the case of running boards, the bolt heads are on the board side and the nuts and lock washers are on the frame side. There is one notable exception and that is the bolt for the running board brackets is on the frame side with the nut and lock washer underneath. No flat washers were used and all of the fasteners had an S2 finish (black oxide)
There was no anti-squeak (webbing) between the running board and the chassis frame on passenger cars, only on commercial vehicles with all steel boards.
To round out the running board fasteners, the rear fender-to-running board carriage bolt heads were on the fender side and the front fender-to-running board hex bolt heads were also on the fender side.
