Forgive me for my lack of knowledge of old Buick’s, I’m new to the site and hoping someone could help. I obtained a 63 Grand Sport Skylark from someone that owed me money. Was a near complete restoration. Has a 401 and the dual path transmission which I was told was rebuilt during the restoration. Got the car running, whenever I put the car in drive or reverse it will stall. It acts like a manual transmission that was started in gear. I’ve only found limited information on these transmissions but from my understanding of them the torque converter can go into a lock up, I’m wondering if it’s stuck locked up. Also wondering if there is some sort of adjustment that could cause this. My guess is something was put together incorrectly but I wanted to get an opinion before I remove it and have it torn down.