John, late back into this thread, but it seems to me that my 24 DL had that Williams peep on it when I got it from my buddy and I assume it was d&t at some point for the installation. The 24 is back home in the safe or I could look at that sight to see if there is a number on it, but I think that it was made specifically for the 24 because the bottom is recessed to mount low to the receiver.
