I did. Everything looks fine. The old spark plug looks fine. There's carbon buildup in the threads, enough to where it looks like it would be sealed. Whatever is happening I don't think it was coming from the spark plug.

The noise leveled back to where it was before; the pitch probably changed because i ended up hitting the actual source a few times getting the coil out.

​​​​​​​I poked around for another 15 minutes with the stethoscope. It's still the loudest just under/around the coil, or on the bolt that secures the coil...like that bolt is amplifying the noise. And i say "loudest" meaning places i could touch with the stethoscope. Having replaced those parts, they're obviously not the source.

There's this black plastic thing housing something back behind....you have to go at that coil at a 45 degree angle, so "behind" the coil at that angle. I hit it a couple times with the scope and it was just as loud.

Idk. Barring an answer in here, I'm either going to hit up the parts department at the ford dealer down the road and have them print me off the schematics and exploded views of what all is behind there, or I'm going to hit a salvage yard (again) and start taking apart an engine.

 

After hitting up a parts department and local Ford dealer and going over some exploded views with the kid behind the counter, we got it figured out.

However, I'm waiting for the symptoms to present themselves again so I can do a single video detailing the problem and solution. Seems like there's an awful lot of threads that just stop with no verification regarding which one of the last four ideas given to the OP was the right one.
​​+-+-+-+-+
Incidentally, there are approximately 1,763 threads talking about some kind of shake that starts at 45-50mph and gets worse the faster you go. I happen to have that issue too, so while we wait on the whistle, let me lay this one out.

​​​​​​Key piece of data: Truck was fine until i clipped a curb right at one of the drains and at the perfect angle to not only shred the two pass side tires, but crack/break parts off both aluminum rims.

Doubt it's a balance issues, or any of the first 5-6 items we'd normally look at diagnosing. Not balance, not driveshaft, swapped tires around (still looking for a replacement rim so running on spare rim). Most likely something damaged at front suspension since that's the area that took the brunt of it.

If you know the answer, send it. I couldn't find one in the threads. If not, help me remember this diagnostic step:

​​​​​​If I jack the front passenger corner up and wiggle the tire, if it wiggles up and down, that means ??? is damaged or worn, but if it wiggles side to side, that means ??? is damaged or worn.

 

My apologies for not getting this up sooner. It took a long time for the symptom to come back.

See video for diagnosis, solution, and thank you to everyone who pitched in with advice.


​​​​​​TL, DR/Don't have time for video: Whisitling-whine that sounds like a pierced vacuum is caused by the intake manifold (someone correct me if that's not what it's called) either cracked or the seal gone bad. Test to find which one it is by spraying source of sound with brake clean. Still whistling? It's cracked and needs to be replaced. Whistle gone? Replace the seal.