For a quick turnaround, there is also member sanndmann3 here that sells them complete. He does the junkyard-crawl and sells them at what I hear is still a pretty reasonable price for keeping your hands clean.
That said, your idea of the whole vehicle is not bad either, especially if you can use some of the other stuff.
For the front accessory drive though, I don't think mileage will matter in your case. At those 200k-plus ranges, it's going to be hit-or-miss as to whether you need to replace all the wear items or not, or if they have already been replaced. Or not...
The pulley bearings might wear out in as little as 50 or 60 thousand miles. An alternator might last 200k or more, or it might be done at 120k already. So the alternator might be junk, or might have been replaced recently with new.
You'll just have to look at those things carefully. If they all look original, they're probably all on equal footing. But if some look to have been replaced it's a reasonable bet (but still a gamble) that you can use them.
Remember the water pump too, as that is part of the Explorer front drive system.
Alternator, water pump, power steering pump are all unique-ish to the Explorer.
And all that same stuff goes double for the engines. While you might find a pristine Explorer engine at 250k miles that's ready to bolt up and go in your Bronco, I still consider anything over 125k to be in need of opening up and taking a peek in there before gambling your time on putting in a bad engine.
Some Explorers were babied, some were rode hard and put away wet. Some were overheated and melted things inside before they found themselves in the junkyard.
It's all a crapshoot over 200k miles.
So as Clint Eastwood used to say... "Do you feel lucky? Well, do ya?"
;D
Good luck!
Paul
