Chevy dually bedside question

I'm fixing to buy an '07 Chevy Dually (current body style, not the new one). I test drove one recently and noticed that on the truck I drove, the whole side of the bed was made of fiberglass. My question is, do they all come in fiberglass, or can you get metal bedsides on these trucks? I would swear I had seen one about a year ago or so that had metal bedsides. Is this an option you select when you purchase one? Any info is greatly appreciated. Thanks guys.

all the new chevys are fiberglass now with the fenders molded in

All fiberglass to my knowledge

i think they are plastic not fiber on new body

Did they ever make the current body style dually beds in metal, or am I just nuts?? Also, I was curious, would a bed from an older body style dually, say a '98, bolt up to an '07 truck? Any ideas as to what all would be involved in doing this?
Once again, Thanks y'all.

The 98 style beds are not as wide as the NBS Chevys. Plus the body lines are different.