I kind of am and I'll explain.
If I were intending to keep the truck forever it would be a different matter, but here's the thing. And this might just be me.
When I look at pics of used stuff when I see radio swapped out my mind says "they messed with it" and it makes me wonder what else did they do.
That's the main reason I want to stay OEM. I haven't changed a thing from stock on my truck.
So that's just me. Granted people do all kinds of things to modify the trucks and I'm not saying that's a bad thing... for instance 5.0L and Explorer rear end - these things work great if done by someone who knows what they are doing like you.
So if I had a Ford 6CD changer to me that's still kind of OEM, but granted, you couldn't get that, I'm pretty sure, in '99.
As to MP3 I guess it still has some use depending on how a person does thing.
As to bluetooth, I can see it would be nice, but my phone already does hands-free calling so as to the phone, all bluetooth would get you is you can hear better thru the truck speakers. And stream music from phone, which might be good, but I'd probably not use it a lot.
I'm thinking at this point the best thing might be get exactly the same radio, then it would be plug/play and I wouldn't be worrying about the fit physically or the fit of connectors/harness.
Or else take mine apart and see if I can get to the lens and try cleaning it. I've run cleaner discs thru it a million times, and it's still working only sporadically and only if the cd is perfect. But all the cds play fine on my computer CD reader so I am saying they are good CD.
So probably after all this I'll likely just go like for like, if I had a working CD that would be one less broken thing and I'm trying to get the truck to where everything works and I'm pretty close. Even though I don't intend to keep it forever (but who knows) not only is it nice to have all working but I feel it makes for a much easier sale.
I know at one point Best Buy had a good deal on a radio I think you posted about it, and they had free install too as part of it. If you were going OEM that would have been a good deal.
I love my '99 it might be hard to part with it but I want 4x4 and at this point am pretty much focused on as late (up to '11) as possible XLT. Problem is if I insist on '11 (rear discs) the prices are still unreal, even for '10 they are horrible yet.
It's hard to say though, I could end up w/ another '99. I guess I researched enough about them that I feel like when I see and drive the truck I want, I will know it.