Hey - I'm having a custom (of my dreams) grill built from an old 60 gallon diesel fuel tank. I want to be able to smoke or use charcoal or propane. It has a nice sized fire box on the side for smokin', is set-up inside for charcoal AND I want it rigged for propane also. That's the problem area. I don't want to buy the regular gas manifolds as when I'm cooking with charcoal that will fall on the manifolds and ruin them quickly. I want the welder to create a manifold out of steel pipe and drill holes in it for the gas/flame. That should stand up to years of abuse from the charcoal falling on it. BUT he's not sure about the size of the holes or spacing of the flame/gas holes. Can anyone offer any advice on this?