A simple search for CW haversack turned up these. Haversacks didn't change much during the war except that the Confederates came to wear many captured federal ones.

http://www.bing.com/images/search?q=civil+war+haversack&qpvt=civil+war+haversack&FORM=IGRE
http://www.cr.nps.gov/museum/exhibits/gettex/exb/existing_DaytoDay/GETT143.html

http://www.horsesoldier.com/products/military-accoutrements/leather/haversacks-knapsacks/6864

http://www.horsesoldier.com/products/identified-items/accoutrements/8271
http://ldhaning.com/knapsack4.php