VIDEO:
YouTube
Ok, so to finally answer DieselChessy's question, here's why I tore into the engine. After reading it you'll see why I didn't want to lead people down 100 different paths from cracked flexplates to rod knock to bad AC bearings to improperly adjusted drive belts lol.
One day when I was pulling into my driveway, I heard the noise you'll hear in the video below. Now in this video, you'll see that it starts out in drive/reverse (doesn't matter), and then I shift into Park/Neutral (no noise at all), then back to drive. You can hear that after I shifted into drive the second time, the noise did not present itself much at all until I gave it some gas and then let off.
With a stethescope on the engine, it can be hear the loudest at the very front of the engine, on either bank, where the head meets the block. No noise is heard at the transmission/rear of the engine.
The thing is, I came across a video on YouTube of a guy with a 5VZ Tacoma who has this exact same noise behaving exactly the same way. He claims that it was solved by replacing the AC bearing and tensioner. I replaced those parts, but the noise did not go away nor change in any way. The weird thing is that the noise did seem to go away when EITHER the PS pump OR the AC compressor or both were disconnected.