I went to MOOG's site and they only list K7424 your vehicle. I tried to lookup RK7424 and nothing comes up. It must be something that Auto Zone added to part numbers.
2012 DodgeRam 1500 4x4, 20% Tint, Running Boards, Class IV Hitch, 14" Win Muffler, Catch-Can, Tow-Hooks, LED Tailgate Bar
2008 Dodge Supe Bee, Catch Can, Backup Camera, 20% Tint all windows, CAI, AFE Filter