I have a Alpine 7909 and was trying to get a Alpine changer does anyone know what changers will work.?

I have a Alpine 7909 and want to get a Alpine Changer.I know about the Alpine 5959s but how many other models will work with this unit? They have others 5957,5952 and soo on that are a lot cheaper than I have seen those 5959s sell for and what is the difference in these models or other models that will work with this 7909 unit?