I am not sure what old style connectors are. N connectors for LDF6 are pretty inexpensive in the surplus market. The tower pros likely have a number of these laying around if you happen know anyone i
I have been looking for the old style connectors for some 7/8" Heliax I have for *years*. They are rare. The hardline model number I have for my 7/8" is FHJ5-50A and the 'N' connector numbers are 45A
Some places that sell connectors for hard line: Davis RF and RF Industries sell UHF connectors for LDF-50A. RF Connection and RF Parts sell both surplus/discontinued connectors and new connectors for