[1969 GMC]

The two Eaton thirds I have both had the # of pinion gear over the # of ring gear teeth stamped on the outside of the third, so that it looked like a fraction. I don't have them at my house, or else I'd go out and look to see what they were (I have 4.57 and 5.14).

If memory serves, they were not stamped in the same place, and I had to clean them up a bit for the stamps to even be legible. Hope this helps.