I have a '90 V6 RS with a 700 trans and when I get moving about 20 mph, I heard a whine that sounds as if it is coming from the transmission. It countinues to increase in pitch as I accelerate, or when I move the shifter to neutral and rev slightly the sound increases as well. It does not quit until I am moving less than 20 mph, and is quite at an idle or reverse. It shifts fine in all gears, and covertor locks normally. Sounds like maybe the pump in the trans??

 

It could be a bad converter, plugged filter or a bearing in the tranny. If it goes away in 3rd but is ther otherwise then it is the planetaries.

 

The sound does not go away unless the car is moving less than maybe 20 mph or so and not under a load. It goes thru all the gears just fine, and I do get lock up from the converter. I am going to try the filter change first, as the car has a lot of miles on it. Also, when you coast in neutral from 50 mph or so the sound disappears too. Thanks for the reply transfixleo!