5R55S Torque Converter Grinding while seating

[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:

View: https://www.reddit.com/r/Mustang/comments/1rj1jgp/help_with_2009_5r55s_torque_converter/?utm_source=share&utm_medium=mweb3x&utm_name=post_embed&utm_term=1&utm_content=1

 

[ctandc]

Pull the converter and check out the splines on the converter itself and then check the splines on the input shaft on the transmission. These CAN go bad. Recently had a 4R70W lose ALL Gears at once. The splines on the torque converter failed. Replaced converter, trans works great now.