My vehicle was built sometime in august of 2002 so I guess it has the wiring harnesses. All I want to do is be able to talk and listen through the factory speakers. Do I need a TCU or ULF?

Please help me on this. I can get a TCU on ebay for $50 all day. I don't need to hook up my phone to charge or to voice dial a number. I also don't have navigation on my car.

Thanks a bunch in advace