I mean you have to go to the Download side where you Download nUI.
I don't know if you use nUI or nUI+. So go to the page where you have get the latest nUI Version. There you find the "Archived" Tab.
For nUI+ This is the Link:
http://www.wowinterface.com/download....html#archives (note that you only can access that side if you have been registered for nUI+. For more Informations about that, look on
http://www.nuiaddon.com)