[4reals]

Yeah, so, I get a little compulsive on this stuff and once I realized all stat back box variations were only from sheets C&D I set out to determine how many cards on each sheet had variations. It would have to be an even number. If there were four on one sheet there would be four on another. I found the attached file of sheet C doing a simple google images search. The sheet revealed five manager cards #s 321, 639, 759, 81, and 109. I also know from my own collection that #s 150 & 573 on sheet C have variations and a fellow collector showed a pic of #659 from sheet C with the variation. That makes 8 cards total. That would mean there should be 8 on sheet D. Unfortunately, I couldn't find an image of sheet D to compare. Hypothetically, all C-sheet managers should have variations, unless there is a manager in the same location on sheet D meaning the layouts would be a wash and no variation would exist. Of the 8 C-sheet possibilities, only two are unconfirmed with no pictured examples, #s 81 & 109.

I looked up all the manager cards on COMC and found five manager cards with sheet D codes. They are #s 351, 231, 519, 261, and 291. That would mean there are at least three others that aren't managers. All three are confirmed in my collection with #s 778, 534, and 294. There's the 8 on the D-sheet.

Now I needed to match them up without having a D sheet image to look at. Impossible? Well, I realized if you look closely at the numbers on the back of player cards you can see an overprint of the shadow where the other card's number got printed on it. It was tough to make them out but I found that...
#150 (Cal Ripken) has #351 (Joe Torre) printed on it.
#778 (Danny Gladden) has #321 (Bob Rodgers) printed on it.
#573 (Rich Rodriguez) has #231 (Doug Rader) printed on it.
#534 (Mike Jackson) has #639 (Frank Robinson) printed on it.
#659 (Oscar Azocar) appears to have #261 (Bud Harrelson) on it, though I'm not 100% sure on that one because I don't own a 659 variation and am basing it off of the pic in this thread.
#759 (Bobby Cox) is confirmed to have a variation so he has to match up with a player. The only player left would be #294 (Mike Moore)

That leaves (2) c-sheet managers and (2) D-sheet managers which could wash each other out if they are found in the same locations on the sheet. They are #s 81 (Gaston), 109 (Riddoch), 519 (Sparky Anderson), and 291 (Wathan).

To conclude:
I would love to see pics of variations of #s 351, 231, and 261. I'm confident they exist but they must remain unconfirmed until examples surface. #s 81, 109, 519, and 291 are also outside possibilities but I don't think they exist.