Brian, I second what Rusty46 said. On my '50, I had the track that you show in your second picture. It bolts at an angle under the bed with the track side down. There is then a holder that slides on that track and has a treaded hook to hold the back side up. There is also a shorter arm that bolts over the tire when it is in place. Finding original pieces (other than the one you have) is near impossible. I know that Jim Carter is selling a repro for about $280.00 for the typically missing pieces.
