Do most portable radios contain a headphone jack?
Almost all portable radios have a headphone jack. Even radios that are ten years old or more have a headphone jack so its pretty much standard.
You buy a cord that has the right size Male jack at BOTH ENDS. You put one end (doesn't matter which) into the iPod, the other into the Radio's Headphone jack. You can do this on newer radios, but I am not sure if you can do it on older models. It didn't work on my Stereo system, and it's not THAT old.