Thread: noise

I have an 2003 w body with the non HD 4t64e and I am getting a slight whining noise I believe from the transmission. It only occurs during 3rd gear direct or lockup, and not in any other gear. I was wondering if anyone could point me in a direction to beging trouble shooting. The trans has had synthetic fluid since new and get changed regularly.

my real question is could it be the diff or some worn out bushing inide the trans. It is a slight gear whine, not a pump whine, only in third, third direct