5FDP, I replied here from the April acquisitions thread.
You were right. After careful inspection when I got home, I found the the MOC Hook I bought is indeed a KO.
I include comparison pics here:
Picture of the MOC Hook I recently purchased:
Picture of a knock-off MOC Hook from the auction site selling these KOs:
This is why I think my Hook is a KO:
(1) You were right in that in both pictures, the ASST number is missing from the cardback.
(2) I noticed that the KO Hook is missing his chest factory applied sticker just like the Hook I have (that is the part most unlikely to be removed or damaged).
(3) The bubble for my Hook came clean off the cardback because the glue just dried off. And this is typical of all KO versions of Transformers.
(4) On closer inspection, the Hook toy itself is rather poorly constructed compared with my other Constructicons (all of which have the ASST number on their cardbacks) which I know to be definitely genuine and not KO.
The above backs your initial post here.