I'm actually amazed at just how many variations there are in vintage figures. It seems like every figure (with the exception of POTF) has a variation of some sort.
There're the four different body styles for the Biker Scout (I've only seen three i person), the orange-head and olive-head Bossks, the painted hair/molded face and painted face/molded hair Jedi Luke, and let's not even get started on Klaatu.
So at this point, nothing surprises me in terms of vintage variations.
Also, I'm 99.9% positive that I've spotted a variation on Barada. I've seen figures with two different date stamps, one 1984 and several 1985s. The 1984 date stamp version came with the Jabba's Dungeon playset. I just need a camera lens that's capable of clearly photographing something as small as a date stamp on an action figure.
The only problem I'd have is that the 1984 figure is not in great shape and the date stamp is a little worn down; but still a 4 and a 5 are different enough in shape that it'd be almost impossible to mistake one for the other.