Found this excellent resource online - full of information about US Army Brigades, their structure and a history of the various brigades in the US military from the beginning of the Army all the way up to 2004 - great resource for those looking at various Twilight 2000 variants as well as for those who want more information on how the concept of the Brigade changed over the history of the US Army.
http://www.dtic.mil/dtic/tr/fulltext/u2/a631475.pdf