So I have been doing a motor swap on my 2001 that has a 5-4 Triton I threw a rod is why I bought the new motor will the new used motor I do have somebody else left it in and take the old one out they put the transmission both of the transmission back up the motor was fine when it went in now the flywheel won't turn my thoughts are that possibly he did something wrong when he bolted it back up and it's caused it to seize up but I am just a woman first time motor swap and I'm not sure LOL

 

From deciphering, it sounds as if you had someone else put in the motor?

Did they add oil to it before starting it? Also, did it even move when it was outside of the truck?

 

Good chance the torque converter is not installed correctly.

 

did it EVER run since it was installed in your truck?
.........................yes?..................... .................................................. ...................................... NO?
did/does it have oil............................................... ................................... probably torque converter improperly installed
yes?.............................................. . no?
not a good sign here....................... $$$$$$$

 

This is the problem most likely. Like 99% likely that the torque converter was installed without it being fully seated into the transmission.

And, at minimum, you need a new torque converter.

D