5R55S Torque Converter Grinding While Installing

[feloniusgru]

Heyo! When I try to install the torque converter into my 5r55s, it grinds and won't spin the output shaft, making me think it's not engaging the input shaft. Video shows the noise I'm talking about. Trans is out of a 2009 Mustang 4.0, and it's going into a 2007 Mustang 4.0
I was having a hard time uploading the video that shows the sound, so it can be seen in my Reddit post here:

https://www.reddit.com/r/Mustang/comments/1rj1jgp/help_with_2009_5r55s_torque_converter

Thanks Y'all!

 

[86GT351]

Used transmission? Maybe there is an internal issue with the transmission?

 

[Kev555]

Sounds like the gearing has stripped in the transmission or the splines the convertor sits on? dismantle it, what have to got to loose to satisfy your curiosity unless you can return it to the breakers yard?