If you look up by serial number - I have a 1922 G 9,339,906 back clamp, and a 1923 G 0,100,316 side clamp. I have a manual with a revision date of 4/23 that shows the side clamp machine, so I know that one was not altered.
So far the latest manual I've see with the back clamp is 1920 (looking for one to match my machine) and the latest manual showing a Red Eye is 1929.