[Danr55]

Are you sure it's in the Xmission? I had a similar problem with my car. 428 with a TKO 600. Everytime I jumped on it, it shook like hell and when I accelerated smoothly, it only shook a little bit, but you could definitely feel it. Checked Ujoints, drive shaft, engine mounts, rear end.......finally because I had nowhere else to go, I replaced the harmonic balancer. Everything went away and it now runs smooth as silk.. Just one more thing to consider.