When I did my last F-100 I used kiln dried fir. I got a sample of some old bed wood for a pattern and cut the stuff my self on a radial arm saw using dado blades. I'm not that crafty with wood, but it turned out just fine and fit like a glove. I stained it with some oil stain and then put a clear sealer on it. I have no idea what "hackberry" might be. If you have a friend with a radial arm saw who can help you, it's a fairly easy task.