First, I've been keeping an eye on this site for quite a while, as a guest. Thank you to all those who have posted questions and who have answered. You've saved me tons of headaches! Thanks to all!

Okay, so here's what I've got.

1997, F150, 4.2L, 4wd, Manual, Std. Cab, short-bed, 151k miles.
No special adds besides a straight pipe after Cats (keep it under 2k and it keeps growling, over that it's ricey and wakes the neighbors

I've noticed a sound that I can only describe as steel-wool rubbed on solid steel...Maybe a quieted squeal. This only occurs when it's engaged in gear and accelerating. When I let off the gas it trickles away intermittently to nothing, that only takes a second or two. Rolling down the highway I put it in neutral and give it gas and there's nothing. Also, it's more prominent in gears 2,3, and 5. 1st and 4th are barely audible but still there. That noise was there when I bought it, has not gotten worse or better, and does not affect driving.

Is this possibly a sign the clutch needs replaced or somehow adjusted? I've never had a problem with gears or clutch before. (3rd manual of mine) I've gotten a few different opinions but nobody has heard anything like this before.

I wasn't raised around vehicles, but if something needs to be done then I'll do it.

 

Possibly u-joints, rear or front differential, or transmission. I would start with the first, and check front & rear unless you can pinpoint the area the noise is coming from.

 

Agree ^^

If you go to neutral and rev the motor you have pretty much eliminated everything prior to the input shaft to the transmission.

If you leave it in gear and press the clutch pedal down and then rev the motor, what impact does that have on the sound?