The rumble seat side cardboards were attached to the rear of the front seat on Roadsters only. The black angle bracket was riveted to the side cardboard with black enameled 9/64" tubular rivets. The assembly was then fastened to the rear of the seat with three black enameled round head screws. The seat was attached to the three angle brackets with 3/16" x 1/2" unfinished square nuts and lock washers.