It appears the latch is a long bar with a hook on the end. To close the gate you first close the gate, then swing the bar's hook into the loop welded on the gate, and finally drop the end of the bar into the angle iron catch. There is a piece of angle iron above it, likely mounted with a single loose bolt/nut, that acts like a keeper to keep the bar from jumping out and stabbing some import in the opposing lane.
Nice truck Jamin, 7.3? You see my thread on 2-stroke in it, I love it!
Yeah, the 7.3L is the way to go.
Brendon. What are your dimensions for the chip box? How thick are your aluminium sheets?
I have bought metal from Metals Depot. Have you heard of them? They seem to have good prices.
http://www.metalsdepot.com/index.phtml?aident=