Top is a factory pack for a factory swing down gun.
Bottom is a factory pack modified to fit a shelf gun. Note the large cutout in the right lower corner. It is NOT the factory pack for swing down. It is on yours and my shelf pack.
Also note you can clearly see part 19 and part 26.
I was in err when I said I saw the trip lever. I looked at photo on computer (was on phone), and it is not their on yours or the others.