Visulize - as the hammer is moved to the "Cocked" position, the cocking indicator is pushed rearward and appears thru the hole in the back of the frame. It is spring loaded to return when the hammer is dropped.
I've been told that some bullseye shooters felt that removing the cocking indicator mechanism would make the gun shooter better somehow so it was not uncommon for them to be removed. Perhaps the one on your older gun has been removed or disabled.
Can one tell from the top when slide is removed? Also posted a question about your picture of view from the top of the 5.5" barrel in one of your other threaths.
Can one tell from the top when slide is removed? Also posted a question about your picture of view from the top of the 5.5" barrel in one of your other threaths.
Yes. Why don't you remove the barrels and slides from your two guns and compare them? The cocking indicator will be between the hammer and the rear of the frame.