Eliasks

Hi first time posting, I have a 2015 cls63s and I put a stage 1 on it. Was doing donuts on dry asphalt ( yes I know stupid) and heard loud clank now drive and reverse are acting like neutral I pulled the trans and pulled it apart everything looks good oil was clean (recently changed) clutches had plenty material no heat what could’ve went bad? Anyone have this problem before? What’s the best course of action? Rebuild it? Buy a new one from Benz $6800 before tax used ones 4-6k. Just stuck on what to do any merc techs? Anyone in Jacksonville Florida who does trans rebuilds? The code I read from the trans was p0730

Cammer88

Sounds like broken output shaft.