When I looked at that ebay listing of "glass memory" it pointed me to another item, https://www.ebay.com/itm/265623663142 -- described as "core rope memory". Obviously it isn't -- it's conventional core RAM. Interestingly enough, it seems to be three-wire memory (no inhibit line that I can see). It looks to be in decent shape. No manufacturer marks, and "GC-6" doesn't ring any bells.
paul