Vatozone clutch. Jasper is correct. I sent him (Jasper) a link on this: Back story, I was cruising at highway speed, let off and went into decel for my turn. Really nasty squeal came from trans/firewall area. Took decel load away and it quit, make my turn and play with it some more. Did it again during decel in 5th, nothing in 4th, came back in 3rd. So kinda started wondering if it was a counter shaft bearing. Kept driving the truck to work for couple weeks and around town to get lumber etc while researching it. The squeal became more common, started doing it under acceleration in 4th, 5th, some times 3rd. I came across this thread while researching :
http://www.ford-trucks.com/forums/1362045-zf5-very-strange-problems-searched-for-hours-4.html
Symptoms match to the T. I was a bit skeptical a clutch would make that noise. I had a brief discussion with Russ as he is in that thread and experienced the same thing. I had some disengagement issue at first so two people saying clutch made it something to check. The bad clutch engagement issues came during this period while researching. It got so bad that yesterday I had to shut the truck off, put it in reverse and start it again. It was missing 3rd bad, missed 5th a few times and did not want to go into 1st at a stop. So apart it came today. Just like the guy in the thread, hub separation. Replaced the release bearing and pilot while I was in there.
His video:
http://youtu.be/-7LKE0XTwng
After replacing: no more squeal, roll over noise seemed to have cut down, pedal is much easier(wasn't that hard before).
And I'll add that's about 4years driving on that vato zone clutch. Mixed city/high way and some abuse