There is no universally agreed symbol but the following are used:
cubic feet, cubic foot, cubic ft cu ft, cu feet, cu foot ft³, feet³, foot³ feet^3, foot^3, ft^3 feet/-3, foot/-3, ft/-3 CCF for 100 cubic feet (C denotes centum, hundred. Used in the billing of natural gas and water delivered to households.) MCF for 1,000 cubic feet (M denotes mil, thousand) MMCF for 1,000,000 cubic feet BCF for 1,000,000,000 cubic feet
as you can see, M stands for 1000. So MCF means 1000 cubic feet. (Wikipedia definition)
GDN Price at posting:
7.0¢ Sentiment: Hold Disclosure: Held