There are some important unknowns here. How often will the truck be used for gravel and dirt loads? Will other loads be dumped that could cause gouging of the wood (such as rocks)? What does looking good mean, and how often could a wood bed be maintained to keep it looking good? Materials for a steel overlay will be costly; securing an overlay (with studs or flat-head bolts) will be time consuming; Putting an overlay on and removing it will be time consuming, a lot of work, and an opportunity for getting hurt; and you will need somewhere to store the overlay when not in use. I spent some of my growing up time hauling and helping to haul sand and gravel for farm roads. A wood bed works fine, but it does wear at the surface, and gouging can be a problem when shoveling is involved. So what is an afternoon of "painting" a wood bed worth compared to creating, using, and storing steel overlay panels? And, in my experience, the looking good part of working truck ownership requires more maintenance on the rest of the truck than on the bed. I do remember that linseed oil seemed to work well at keeping weather at bay, but know nothing about adding color to it. Also, what else might be hauled that would require working on the bed. Sometimes it is better not to have your load sliding around, and steel can be slick - especially when it is wet. Even gravel trucks do more than dump. They also have to stand up to loading and hauling, sometimes on rough ground and in close quarters. And they need to reliably run, go, and stop. Personally, and I know that this is just an opinion, I have much more appreciation for a well maintained working truck than a perfect show truck that is only meant for looking at.