I imagine that must be frustrating after all that work!
Did you reset trans adaptations before the test drive, and do the final fluid fill at operating temp according to procedure?

 

yep! reset the adaptations, and made sure the fluid was topped off a few times, double checked the level while the car was on and off blocks. it took about ~8 quarts. still no dice.
I still think its the trans, but can the transfer case, or a bad torque converter cause this? A little bit of fluid came out of the tcase breathers, but I can't imagine it would cause anything like this.
I don't even have much power in first or reverse, its slipping a lot, and feels like its not even attempting the second gear.

 

Is the TC seated correctly into the trans ?, if not the oil pump wont drive and it will end in a failed transmission.