Audio Systems: Replacing radio/cd unit for Dodge Ram/Infinity, hefty price tag, infinity speakers

Question
My son has a 2004 Dodge Ram with "infinity sound system." The head (CD player) has gone south on the unit and I keep getting confusing opinions as to whether or not (and if, so what kind) of after-market unit can be put in as a replacement. Have been told you have to replace through Dodge dealers (hefty price tag - around $700 to replace the radio and cd player). "Experts" have told me that you can't just replace the head, you have to also replace the speakers (which are working fine).

Question (finally...) is there a unit that is compatable with the infinity speakers? If so, any suggestions? And, if not...any suggestions?

Thanks,
Jo

Answer
All the "Infinity" sytem adds on the Dodge ram 2003 to 2005 is a big silver speaker level amp behing the glovebox. You can install any DIN sized headunit using a proper plastic install kit, adaptor harness and antenna adaptor. The fit kit, harness & plug should cost less than $40.00 at most decent car audio shops or places like Crutchfield on-line. The install is pretty easy, just make sure you remove the one phillips head screw behind the bag hook near the glovebox before pulling the radio trim /heater control assembly off. Oh, and hook up the power antenna wire so the amp comes on.