Broken heart
I thought the 63 fenders were the same but everything between them was different up front. Glad you got the fender and nice grill. Im wondering if the 64 valence could fit and adapt the 63 parking lights? No history on a 63.
I hit R in a 727 and the 340 motor just stalled. Nothing locked up. Im betting a rear end part blew and locked the carrier. I cant picture an auto locking the output shaft with enough force to freeze the differential? Even throwing it into park would shear the park pawl long before the diff would lock up if it ever found the teeth. Check rear....