CMP and SA ILS mainspring housing

Is the Springfield Amory ILS (locking) mainspring housing legal on a ball gun?--  The rules say: arched or flat and non-adjustable(ILS is not adjustable-it's lockable). - - At one place in the rules it says (not an exact quote) that anything not "as-issued" has to be specifically allowed. -- I emailed CMP with the question and they sent me the section about arched, flat, non-adjustable. --- I'm thinking the "not as-issued" could be what might dis-allow it. ---Mostly curious, my ball gun has a standard housing.
Thanks, Russ

The ILS housing is not different from a standard one except for that rotating plug.  I have replaced the top plunger and installed a standard stop pin and the housing is then no different than a standard one in my opinion.

its legal to use or change it