1965 Imperial cv/double cardan ball and spring

Well I just found out that my 1964 imperial actually has a 1965 drive shaft! I don't know if the original owner placed it on the car or If it was from factory (my car was produced in June of 1964)

I'm about to replace all of its parts,u joints, ect. but does anyone have any part numbers or links to a new ball and spring for inside the cardan joint?

Thank you in advance!
Author: 64Imperial