box : 1976 - 1978 - With logo "CORGI"
Last box : 1979 - With logo "corgi" in single case letters, as opposed to capital lettering
Early version of the box (with corgi in capital letters) have "National Periodical Publication 1966" copyright on the back,
Last version of the box (with corgi in single case letters) have "Dc Comics Inc" 1976 copyright on the back.
If you look at the pic of the prototype batboat, you will notice that the tin effect was going to be kept either side of the fin, whilst the fin lost the tin completely.
The type of Batboat that appears on the back of 76 issues was a prototype and was never produced, if you look at the back of your orange fin Batboat box, you'll notice that the Batboat pictured still has the same bat-stickers as the tin fin, and it still has a beacon. This was the prototype assembled, and they wanted it cheaper so removed the beacon and changed the design of the stickers. I daresay that prototype is out there somewhere, yet i've never seen it :