You can find tanks for sale. Some of the main guns work.
http://armyjeeps.net/armor1.htm
http://www.tanksforsale.co.uk/Tanks_Trucks_Jeeps_for_sale_page.html
http://armyjeeps.net/armor1.htm
http://www.tanksforsale.co.uk/Tanks_Trucks_Jeeps_for_sale_page.html