You know, that you can do an "I-pod" plug install on your factory radio for about $5 and an hr's time? In the case of all of the stock radios you remove the center wire on the volume cont and run it to a mini earphone plug with switch. Hook the old wire to the contact that will disconnect when the plug is inserted and the hot wire (headphone out) back to the center pin on the radio. You will also need a ground (second conductor on a mono plug). This will work for an AM radio but you will only get one channel. For a stereo (AM-FM) there are 2 volume pots ganged together and the operation needs to be done on both, but this will give you 2 channels (stereo). The volume will be controlled from your I-pod.
If you like the volume cont on the old stereo to work for your I-Pod input you can hook your input up to the center pins on the radio-tape switch which is on the tape head pre-amp board (a separate small ckt board that the tape head plugs into). This works really well on the old AM-8 Track. You get much better level this way also. Works great for FM too, jut plug in a FM walkman.
Just remember that on an AM you have 1 wire to switch and a common ground and on a stereo you have 2 inputs to switch and a ground. The radio's original AM, FM, or tape will work when you unplug the mini earphone plug (if you wire it correctly).
Russ