Get yourself an original set of Anco's or Trico's. They will be a bit expensive. They will have the proper adapter pieces (red, blue, green) in the boxes for converting your wiper shafts to accept the more modern style of arm. Look in ebay and search for "vintage Anco" or "8" Anco", "9" Anco", etc. I'd do it for you but the links would just get deleted anyway. I had the same problems with my Jim Carter wiper arms and blades. Once those went into the trash, i got some NOS Anco's, and they have been on and in the right place for many sustained runs over 80 MPH and a couple short ones over 100mph.
140699853568 ebay listing. Look at the back of the box pictures to show you how it's done. You must have those adapters included in the package.
