Did i damage my 727

You say it has a problem when it goes into third; and also that reverse seemed like it might be delayed. Those two problems are both in the front drum. This will be interesting because I can't imagine what would cause the vibration only in third, no matter how bad the direct clutch is; unless it's chattering when it slips. When you take it out, check the end play before you take it apart; even a rough estimate; not necessarily with a dial indicator. And don't order any parts whatsoever until the two front drums are out. And don't take the retaining clip off the front of the output shaft unless absolutely necessary; no sense in getting into this trans further than needed. Fingers crossed.