I just picked up my 3rd HS5 cab and it's diffrent from my others.
This one is not on a tall pedestal base like my other two. It is thus missing those big bolts on the lower sides of the machine.
The 25" monitor is also bolted to a metal frame like yours as you mentioned. It's complete so I can take pics of anything if you like.
Just let me know. It has a full back door also and has a small square hump in the back where it's looking kind of odd. I'm not sure if this back is original since it's raw particle board.