I had one on my 83 while it's sat for a couple years.... I was worried about it sanding my paint off too so I got one a little better than middle grade. I think there was only one "level" better than what I got. I, however, cannot for the life of me remember the brand.
I do know I got it on eBay and it was around $75 or so.
It didn't quite go to the bottom of the cab though BUT it was designed for a newer style CCSB since they didn't make such a creature in the 80s. It did good though. It was better than the pollen and tree sap all over it!
It also wasn't completely water proof, just water resistant. It was porous to let it breathe. It took a long or hard rain to get the truck wet but even still itwasn't soaking wet... just damp on the underside of the cover. It was also mold resistant.