My Cuda had the 904 in it when I bought it, and doesn't it free up a good amount of horsepower? With everything I have found so far, I'm thinking the snout on the torque convertor broke. It's happened to me before but with different symptoms. I have been using a /6 convertor and if this one is broke I think it's time to upgrade the convertor to something stronger. With the driveshaft out and on a lift, it's no job to drop it.