Only happens when in gear. Not in P or N.

Can be heard at around 1100 rpm and then again when cruising at around 35mph. Also very noticible if i put my foot down.

I guess i need to drop the pan and see whats going on in there but i cant do that for a few days. I was just wondering if anyone had any ideas what it could be, and if i should be driving the truck even? Worried im gonna make it worse by driving it.

It shifts compleatly normal. Drives normal. Just the noise...

 

I know its coming from bottom of trans cause i had a buddy get in. Put it in drive and brake torque it to 1100 rpm while i got under and listened to where it was coming from.

 

I would stop driving it, till I knew what was going on. If you have something else to drive..... park the truck.

 

Drop the pan and see what falls out.

 

Doesn't sound good. If it shifts fine, It PROBABLY (but theres a change it could be) isn't part of the valve body or springs. Could be coming from the front set of clutches and gears. The reason I'm thinking this is that when bearings or any type of spacing or guide hardware goes out on a vibrating part, it is not always noticeable except at certain frequencies of vibration. Your grinding could be a worn or broke part that only makes itself evident at 1100RPM due to the vibration... Or I might be over-complicating it... HMM

 

Oh come on, we all know you would never do that........

 

On the contrary :P ... Im am a master of overcomplication lol