The early ball and trunion type tranny flanges where bolted, held into the tranny output shafts by a large nut and a locking flat flange type washer.They had 4 studs that the driveshaft end slip over and was held onto the tranny output flange by nuts. Do you have a picture of your T10 output yoke or flange? All the other brands back then had went to slip in type tranny yokes that used standard U joints, not ball and trunion U joints like Mopars had that year