In Sportscaster Series #10 I have cards from print runs blank, "A" and "B".
For the first print run, I only have 13 of the 24 cards. All of these were printed in Italy. Is there a blank print run from Japan? Yes, I found one with a blank print run from Japan.
I do have all 24 cards from print run "A" and "B" so I can at least compare them to the 13 cards in the first print run. Here are the three back variations I've seen.
10-03 Nadia Comaneci - all three have different awards added
10-09 Mario Andretti - 'B' has added text and awards from 'A'
10-11 Wrestling - John and Ben Peterson - 'B' has added text
10-22 Nordic Skiing - Thomas Magnusson - 'A' and 'B' have added records??
Stay tuned for more variations.