Those work if your OEM head unit has the capability to control a CD changer. buzzworth didn't indicate whether or not his Ranger head unit had CD changer capability, but I assumed it didn't since he was looking at the FM modulator.
If you have an OEM had unit without CD changer control capability or Aux/Satellite radio input, then your only options are:
1. Wireless FM Modulator
2. In-line FM Modulator
3. Replace the OEM head unit with an aftermarket unit
Unfortunately, that's where I'm at with my 2004 Pioneer Adrenalin head unit. I've tried Option One, and am now using Option Two. It's working pretty well, but I may eventually replace the head unit with something like a Pioneer Avic-D3 in order to gain real iPod control and navigation. But that's
much later down the road, after I'm done with other, "higher priority"
mods.
Or, I may just end up buying one of those new "Second Generation" Sync-equipped head units that Ford sells for ~$35,000. I hear that if you buy one of those, they throw in a new Sport Trac Adrenalin for free!