Wood bed rear cross sill help

[.030over]

I just pulled my '67 wood bed apart today to see what is shot and what is still good. It looks like the rear cross sill would be alot of work to save. No biggie, I'll just buy a new one. But wait, no one lists one for a wood bed??? What is the difference in the wood and metal floor on the rear cross sill? Does in fact, no one make one for a wood bed? Could a metal bed sill be fab'd into a wood bed sill? What's the chance of coming up with a good used one?

Scott