[SOOTIE]

Take the tuner off and return it to stock, if your transmission survives, then it's your tuner.

I would bet your tuner is killing your transmission, FWIW...

i sure would hope a built trans would be able to handle a simple tuner. try different tunes maybe but the bottom line is that this type of story is not unheard of when it comes to ATS trannys.

go with a Twisted Diesel or Elite or RCD or one of the many trusted, proven trans builders.