Unclear what year vehicle is addressed in the original post.
Early years were Hitachi, later years are AMK.
I can tell you that my 2013 identifies as AMK - per the IIDTool.
And on another post in this group, someone stated that 2014 onwards are AMK.
Rover cannot tell me which one is in my 2016, even with the VIN, they can only tell me that the part numbers for new compressors are matched to the VIN and whatever is in the box will be correct.
But since Rover is literally $1K more than say, AB - (even for a factory OEM AMK at AB), kinda need to know what's in there before we purchase from AB, or our other favorite vendors...
If purchasing a new pump, the new pumps come with new dessicant canisters already installed.
Remember to inspect the air intake filter and either clean or replace as indicated.