My guess is on startup its coming from the G56 the truck is in Neutral and the pitch of the noise changes when I push in the clutch. Once I back it out and head down the road it goes away and really have not heard it since Wed. Maybe alittle this morning. The Clutch feels fine all gears shift smooth.
I switched out the G56 fluid about 1 year ago to the Delvac 50w syn. add the additional Trans Cool plate at the same time and all has been good alittle stiff in the shifting category on below zero mornings. Also last month pulled Solder Summit 3 times going from Price Utah back to Sandy with 10 tons of square bales Had to grab 3rd gear to keep the EGT's where they needed to be but she has been a champ.
Now this out of the Blue screech any thoughts greatly appreciated.

 

Throwout bearing.

 

^^ What he said.^^

I would consider replacing the clutch/fly wheel depending on how many miles you have on your rig.

 

Thanks and that is what I was thinking.
But it shifts Great all gears from standing still to going up a Parley's this weekend.
New ceramic clutch just 20k miles ago.
Any other Possibilities?
Its this low droning whine On start up some days and not others.

 

Go ahead and check your bearing. I've had bad ones at 5000 miles.......

I miss the old greasable ones in the old IH and Chebies.......

 

Yep it was my Throwout bearing. took me about 8 hours being a first timer LOL.
Although Can someone tell me what the torque should be on the bell housing bolts I did 30lbs enough not enough??? Thank You