Well, to start out, the last few days I could hear a slight howling noise comming from under the truck when I decelerate and today on the way into work something lets loose and sounded like ball bearings rattleing around under the truck, it was the most awful crunching noise I ever heard, the howling got super loud with a bunch of clanking that seemed to get louder or quiter the faster or slower I went. I limped it about a mile down the road to my job and all the while the transmission was shifting fine and tranny temps were norm (170). When I come to complete stop, the noise is gone with engine running while in drive. So I put it in park and gave it a few revs and no noise. It only happens while the vehicle is in motion so Im hoping its the lesser of two evils and hope its the rearend and not the tranny or TC; it was really hard to tell if the noise was comming from front or rear. No fluid was leaking anywhere. I had it towed to my mechanic..what do you guys think? Do you think its the rearend? I really hate posting in this section..its usually nothing but trouble

 

sounds like when my trans went out in my truck. it was an awfully loud, almost an old ford expedition been beat to hell kinda howl. It would go in to gear just fine and all so we thought it was the rearend at first too. Sorry to be the reaper on this one bro

 

I dont see how this could be the tranny, I have had 3 transmissions go bad on me, and everytime it would just start to slip and get worse or it would have problems in a certain gear, the only way I think it could be the tranny if it were in the TC or maybe even the flexplate. I have blown one rearend and it was howling pretty bad before I had it replaced, thats why im leaning and hoping its the rearend.

 

also in order for me to describe the noise a little more accurately, I remember when I was a kid and I would put a deck card in the spokes of my bicycle to make it sound like a motorcylcle, well imagine using a piece of sheetmetal in the spokes instead of a deckcard. It got louder, faster, and more highpitched the faster I would go and slower when I slowed down, with a few other noises mixed in.