Hey guys, I was hoping to get some opinions on my current issue on my 67 Mercury Comet Project. It has a fresh 289 that has only ran for the cam break-in. Upon installing the C4 transmission, the motor still spun free with my wrench and allowed me to install the torque converter nuts through the flex plate with no issues. I have since connected the driveshaft to the tranny and rear end. Today I tried to start it in neutral and it locked up solid after turning over for a second. I have no idea why and hope to hear some suggestions. Thanks.