You can order either filter for the QMP602 system. The CBR2-10R will reduce the same contaminants as the CT-2R filter that you previously had. You can read more abou the CBR2-10R filter here:
http://www.waterfilters.net/Pentek/wholehouse/Carbon_Filters/CBR2-10R.htm
To replace your discontinued Culligan system, you will need to order one QMP602 countertop system and one of the CBR2-10R filters. There are quantity discounts for ordering multiple CBR2-10R filters so you may want to consider buying a case of 12 which will last awhile. There isn't a shelf life on these filters as long as you keep them from freezing.
http://www.waterfilters.net/Countertop-Water-Filter-System-QMP602_p_0-565.html
Thank you,
WaterFilters.NET