I just replaced a blown 6.7 cummins with a used one. The engine turned fine before I installed it in the truck but now that it everything is connected it won't turn over, it seems like it seized up. I was able to turn it with the harmonic balancer bolts to install the torque converter but now i can't budge it. Any suggestions

 

Somethings bound up somewhere. Make sure your converter is hooked up right and not somehow misaligned. or not fully seated. That'll do it for sure!