Greg,
I used an old box I found in the bush that was in actually pretty good shape as a template for the box I built. I used the cross sills on the new bed. After I was done, I sold the sides and front panel for $200. Yes, they were very solid but the dings, dents and rust weren't worth repairing to me. A few months after I sold those pieces I saw them come back up for sale on the same classified site. On the classifieds where I live I see numerous 1 tons come up for sale. I wouldn't pay much for a box. A guy could pick up a decent complete 1 ton in my area for $1000 then part out front fenders, hood, etc and be close to $200 difference leftover for the box. Up to you what you want to spend. Hope this helps. Good luck. Be careful, these big old girls worm into your shop somehow! 😃
