Did you happen to have a pic of the other side? The side shown looks like it is ground down some, enough that the edge feature is ground away. The other side likely had the weight number stamped between the bushing and the rivet.
It is possible they are 8AB's as well, as the profile and hole locations are the same or very, very, very close. The 8CA's are a little thicker in the ramp area and thus heavier than 8AB's. If yours were 8CA but ground down enough, then they could be more similar to 8AB.
8CA = .326" thick, 42.8 grams empty
8AB = .306" thick, 41 garms empty
I know you traded them already, but the new owner might be interested in this info especially if you like him and he's here on this forum.