New coax T800?

This is what I use to fish cable through a mirror arm. If I can fish a piece of coat hanger through the arm I can attach one side of the coat hanger to the cable sock which gets tighter the more you pull it and it pulls the cable right through the arm.

 

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.When you are speaking about getting the connector around the corner, are you referring to the connector on the cable that goes to the radio? If so, you will most likely have to remove the connector and reconnect the connector to the coax after it has been run through to the radio.
....Smaller diameter coax cable may make it slightly easier to maneuver but not by much.

 

FME connectors usually slip right through the mirror arm.