greenough 4A from true ames...either 9.5" or 10". best all-around single fin i've found...long base for drive & hold, narrow, flexy tip for maneuverability & "pop".
Thruster Baby! Yes, even on a longboard.... You can turn on a dime that way and hold your rails a little better. Then its like shortboarding on an oil tanker!
Thruster longboards are like Fat chicks on unicycles they dont mix and dont belong together . If you wanna rip get a shortboard and rip on that. If you wanna glide and trim get a single fin log and have at it