This is an inline FM ipod modulator kit, which will work for ipod. It has 3 frequencies, I go with 88.3 FM if memory serves me correctly. Then add a small switch, when you want to listen to ipod as it block other radio stations and all you do is tune to 88.3 FM and it plays your ipod at the selected frequency.
I added the switch and hide it between the drivers seat and plastic console. When you want to listen to the radio, you simply flick back the switch
This is the kit, but I have a different one though for my rec unit. Also the antenna sockets are different on ours and the adapter alone can be expensive but this kit I think by the looks of it comes with the correct adapters, but please do enquire to make sure that it will plug into the head unit
CHRYSLER 300c Grand Tourer Car iPod iPhone FM Modulator Adaptor DS-FM-CHRYSLER | eBay