yes this has been known for along time now..
Gm convertors have a very small clutch lining material that needs replaced around 100k mark.
Now this will very depending how you drive, tow etc, so its just a guess.
But when the convertor goes it does send all the clutch material into the rest of the trans and makes a real mess of things.
My advice, change the convertor as soon as you can. And i know its not cheap nor easy, but itll save your transmission