I was at the Pull-a-Part in Norcross yesterday and they have an '89 (I think) that has a perfect or near perfect bed on it. I think they said $275 for it.
It had a cap on it, which is lying beside it broken, and there appeared to be zero rust in the bed, and I didn't see any anywhere else. No tailgate. Dual tank openings.

If I had the money I'd get it for my '85, but don't so thought I'd pass on the info.