Please follow up if you find anything.

I see some brass ones listed for $75 at

  https://www.heavytruckparts.net/detailview.php?partnum=24489918&vendor=1821960&store=1&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=C65&searchnum=2

https://www.heavytruckparts.net/detailview.php?partnum=24512000&vendor=1821960&store=1&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=C65&searchnum=2

https://www.heavytruckparts.net/detailview.php?partnum=24513709&vendor=1821960&store=2&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=C70&searchnum=2

https://www.heavytruckparts.net/detailview.php?partnum=24529771&vendor=1821960&store=6&oemnum=3027681&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=C65&searchnum=2

https://www.heavytruckparts.net/detailview.php?partnum=24572394&vendor=1821960&store=2&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=C60&searchnum=2

Plastic ones.

https://www.heavytruckparts.net/detailview.php?partnum=43278&vendor=3737711&store=1&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=C70&searchnum=3

https://www.heavytruckparts.net/detailview.php?partnum=24476971&vendor=1821960&store=1&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=C65&searchnum=3

https://www.heavytruckparts.net/detailview.php?partnum=53520&vendor=3737711&store=1&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=C60&searchnum=5

This one is plastic and listed as for a 93 Kodiak $50.00 ?

https://www.heavytruckparts.net/detailview.php?partnum=24538075&vendor=1821960&store=3&partname=Radiator%20Overflow%20Bottle&make=CHEVROLET&model=KODIAK&fc=1&fp=1&searchnum=4

Had the same issue finding original washer bottle that was molded for formed mount under hood.

https://talk.newagtalk.com/forums/thread-view.asp?tid=664736

Maybe one of these could be retrofitted to work ?

https://www.summitracing.com/search?SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=plastic%20radiator%20overflow%20tank

Would also like to find floor mat replacement source.