Hey guys, my first post and first stang, I have the Mach 1 audio system in my new to me 2004, is there a way to attach an auxillary cable to the head unit to plug in an ipod?

 

Not sure about your audio system or if this is what you're looking for, but here's a link I found.

http://www.logjamelectronics.com/piefrd03aux.html

This one says that it converts the CD changer port of the factory head unit to a plug thing that plays anything with an RCA output like iPods or mp3 players, etc. Might be able to find more and I don't really know if it works for your car, but it does look like what you want to do is doable.