I bought a 2005 Focus a while back. ZX5 SES to be precise. It also came with the audiophile package (subwoofer, Sony speakers). Unfortunately, the guy I bought it from said that there was one CD slot in the stack of 6 not working, so in the interest of keeping everything functioning as it designed, he put in a cheap Sony deck and got rid of the original head unit.
... at least he had it installed with the proper wiring so the sub and steering wheel controls still work.
So, now I'm thinking about going back to original head unit. Put my VIN into fordparts.com, and the audio chassis that came up was part number 18D806. It was also in the $600 range. So naturally, I look at other options (used, other sites, etc). I didn't see that specific model number, but there were some similar ones out there. Can anyone tell me what the differences in model numbers mean? All I know is that this had a 6-disc changer and works with steering wheel controls and the sub woofer. That said, if I can get the SYNC unit at a reasonable price, I'd definitely consider that. Not sure if that's a factor or not.