According to the Wiki item list for Blackburrow armour such as the below should drop; but I have killed many thousands of gnolls and can say for sure it does not drop on this server. It is either a server bug or the Wiki is incorrect, and this is not in the classic/Kunark loot table.
http://wiki.project1999.com/Ruined_Gnoll_Chain_Coif
PS. I remember this dropping frequently on live around 2002.