A series of antimony-doped Ba8Ga16Ge30 clathrates was grown as large crystals from gallium flux. These compounds form in the cubic space group Pm (3) over barn, with the unit cell parameter varying from 10.784(5) to 10.9008(6) Angstrom as the amount of GaSb substituting for germanium atoms in the framework is increased. It was found that more antimony than extra gallium was incorporated into the material and that a specific site (the 24k Wyckoff site) was favored by this element. Ga-71 NMR was carried out to determine the siting of gallium; it fills the 6c site preferentially.