Factory radio inputs

On some truck/suv's with the center console, a cassette player was optional with the standard factory CD player. My truck has neither, and i noticed that on the wire harness going into the CD player there are several slots with no wires/pins in it. I can only assume that some of these slots were to be used by the factory cassette player to take advantage of the "AUX" input on the cd player. What I would like to know is which of these "pin holes" does the factory cassette deck plug into; I want to use a standard headphone-type jack as an "aux in" so I can hook up an MP3 player into the factory cd player on the AUX channel

He, he, yeah been there tried that. I looked up the wiring schematic in the Haynes manual and wired a mini din to the proper pins. It didn't work. Spend $40 on an FM Transmitter and go through the FM on your stereo.

I really wanted the slick AUX setup off the stock deck too but, couldn't get it to work. I'm actually happier the way it is now because the FM Modulator that I have also has a builtin MP3 player that reads off of USB Memory Sticks. I just load some tunes on to my Memory stick slide it in to the Modulator that plugs into the Cigarette Lighter and I'm off to the races....
Lemme know if yah want pics....