Those were used on the base of some old CB radio antennas.
No idea where you'd find them now. Maybe scrub e-Bay for an old CB antenna you can salvage.
If you could carefully cut the crimp off the cable end, you could probably desolder the center conductor and replace the coax, if that is what you are trying to do. Either solder the outer braid to the connector, or find a "close enough" replacement for the crimp ring.