For those who don't necessarily want the ipod connection that connects to the AM radio (discussed recently) these guys have a good range of options. I have the Mustang retro AM/FM radio cassette (yes, remember them?)with ipod connection in my Mach 1 and it works great. It came with the car so I'm not sure who/if anyone sells them here.
http://www.casmfg.com/index.htm