Just today a loud grinding sound started coming from what seems like the left side of torque converter. It can be there at idle, or not. But on acceleration or load it is very loud. Tranny is a Turbo 400. Engine is Buick 350. This car is new to me for one month. Several days ago hooked up the kick down switch for first time since I had car. There was no kick down switch mechanism when I bought it. Any ideas? Thanks