Gas tanks are fully functional; no dummy extensions. 2in. stretch over stock length; capacity is approximately 4.2 gallons. Available in a smooth-top style for use with standard screw-in caps or with locking aero cap. Aero cap included; screw-in gas caps sold separately (use 82-E96 style). Smooth top tanks require custom gauge mounting. Accept late-style petcock (22mm). Come complete with all necessary mounting hardware Single Locking Aero Cap.