Thanks for clearing this up. I have encountered a number of these Pam-2 mags that are modified this way and could not figure out what they were for.You have PAM-2 mags that have been altered to be used in the AR15-9mm. Note that the upper sleeve has been totally ground off on one side to make the mag narrow enough to fit in the AR magwell. If they were altered for use in the 9mm MAC, both side of the sleeve would have been ground to taper them towards the front to approximate the trapezoidal shape of the original MAC 9mm magazines. They also have a notch in the side to engage the AR-15 style mag catch.
I have no idea what they may be worth. There is no shortage of better mags for the AR in 9mm and being single-feed mags, they are a PITA to load. I have a half dozen of them collecting dust dating back to the magazine ban days, when they had some value as "pre-ban" magazines, but those days are long gone.