Thanks to both of you who replied for the info. I'm not sure the letters before the 5970, it didn't say anything more on the owner's manual. I'll have to look on the device itself. I got the changer originally with an FM modulator kit, then later I replaced the head unit. I'm going to spring for a new head unit when I go XM, I agree that you can hear the degradation in quality with an FM modulator. Also, I'd love to hear about good places or sites to buy the equipment -- sounds like I need an XM ready head unit, an XM tuner, and an XM antenna. Thanks again.