Gas tank rock guards are one of the first accessories purchased for Jeeps going off-road. I don't think you'll need it for potential damage on gravel roads, but protection never hurts if you might be going into the fields or into unimproved areas. I looked at LMC Truck and didn't see any OEM guard for your C10, but fabricating one from some sheet steel would be pretty simple, either by bending it up into a five sided box with mounting tabs to the crossmembers, or welding one from pieces.