Yep. The dihedral tail unit was introduced after the first couple production batches, and was retro-fitted to some Mk1s also. There were many external changes to the Mk1, and the main differences on the MkVI were internal, often making it difficult to tell which is which, if the serial number is not known. Even internally, in photos at least, often the only way to tell is by the cannon feed - the Mk1 being drum fed, and the MkVI belt fed, from four ammo tanks, as included in the Tamiya kit.