Thanks modelman, I'll get some of that and try it also. This dump bed is a learning process. I'm sure in future I will be making a better looking bed. Got some more done,
Clamp, position, check,,, reclamp, reposition, recheck,,,,,,,,
It did take a bit of time on the belt sander to get the back flat so gate would sit flush.
The piece left in bed was just to keep square. I'm using magnets to keep gate closed. I did incorporate a tunnel in the bottom of bed to accept actual gate locks if I want to try that. That might become another experiment and learning project.