While browsing youtube eating lunch, I came across a group of videos by a youtuber named Jax Austin. In the videos he showed the process of tear down, inspection, rebuild and dyno of an mt643 transmission.
He's upgrading from an at545 because it had some issue(I don't recall what)
Pretty sure he has a skoolie, although I'm not sure if he's a member here, but I thought it was kind of a neat thing for those that are mechanically inclined and skoolie interested.