have a growling/grinding noise in my 4l60e when driving EXCEPT when in drive at cruise, noise there when accelerating thru gears until drive then goes away and comes back when in overdrive, also in reverse. about 85k on trans, not abused, dragged etc. just a driver. how can I try to diagnosis what it might be without trans removal?

 

Since it does not happen in D3 3rd gear or 3rd in OD position I would have to say you have a planetary going and its time for a trans I am afraid

 

I was afraid of that, oh well sometimes you have to pay to play