Rick already said the 4L80E will not Fit. No Room. The Torque capacity was far exceeded Grumpy 200R4. Once Rolling down the Road driving wheels are still gripping hard. Huge wide tires on the T. Low torque trans from your own charts. One I found too right from the Buick Grand National Website. All had 200R4. Only 1 trans with stock high torque capability will bolt right into the T. Rick does not want. TURBO 400. He does not make enough power to break it even in stock form TH400. Still has a safety factor of 2: 1 ratio.