I don't think Thick Grizzly Bear Skins shouldn't be dropping in classic; they were added iirc during the massive tradeskill patch in May 2002 (
http://www.tski.co.jp/baldio/patch/20020508.html ), and comments / dates of confusion about why Grizzly Bear Skins weren't dropping on mobs they used to drop on seem to corroborate this (
http://everquest.allakhazam.com/db/item.html?item=3240 )