I have a 2005 Magnum SXT with 3.5L V6 24V High-Output Engine and a 4-speed Automatic Transmission. I am getting a rumbling vibration when I take off from a standing start. It continues as it shifts through the lower gears and almost disappears in the higher gears. Taking her to a tranny shop on Monday, and would like to get some ideas what to expect when I take her there. Anyone have some input?