I see the Concord was the antenna on the Air Stream.. Now I do not know if it is the same one but there used to be a company in Battle Creek Mi. one of the engineers was retired from her Majesty's Naval Service (British navy) Submarine service. the joke is "When he designs a seal IT DOES NOT LEAK but alas, that was not his part of the design.. G2CWL was his call.
Do not know about replacing them but the antennas back then were 300 Ohm folded diploe type as I gathered from a story he told
Modern antennas are 75ohm. Conversion is simply they make converters you can get at many dollar stores. (Balun or Transformer on the label).
300 ohm cable is flat.. 2 wires, side by side 75 ohm is round, coaxial.
I would suggest replacing the antenna cables and splitters
Shoudl be easy to do.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times