Inner Universal Joints

I have seen many Cord cars but I'm always left with questions. So I'm wondering if or when engineering changes were made to the inner universal joint bolts that secures the housing to the transmission? My Beverly with a build date of between January 7th and the 16th has the bolts without the slotted screwdriver head in them. They are the thick hex bolts for this time line. Some cars I have seen have the slotted hex bolts and some do not. Anyone care to weigh in on this.


Gary Parsons