If you bought a detachable tour pak rack in 2004 it is no longer available. The 2004 version required a rear docking point be added. The front docking point was the same as the detachable back rest that is stock. Below is the list of components I bought in 2004 for my bike.
53155-04BKM King Tour Pak
53107-96 Detachable tour pak rack
52892-98 FLTRI/FLHRC LARGE TOUR PAK BACKREST
53127-96B KIT, REAR DOCKING MOUNT
53598-88A KING TOUR PAK LINER
90743-88 Base Foam Pad
The 2005 FLHTSCE has a different docking system for its detachable tour pak. That detachable hardware replaced the version above. The newer system has the same rear docking point, but the front docking point is different. The 2005 came with all the docking points installed for either the tour pak or the backrest. The front and rear docking point for the tourpak would need to be added if you wanted a detachable tour pak for your 2004 bike now. According to the H-D website this is what is needed for the detachable tour pak rack now.
53276-04 Detachable Tour Pak Rack
53746-97B Rear Hardware Docking Kit
53127-96C Front Hardware Docking Kit.