As the title says, this is a working 3.0.9 and 3.1 old school stealth animation for undeads (I don't know if it works for any other classes as I haven't tried, I did not make this model edit, just sharing with permission) the guy who made this model edit is a guy who I met on WCM (Essentheymy) all credits goes to him.
http://www.filefront.com/14592539/patch-3.MPQ
Edit: Updated the download
Big box...