GE CB handheld advice

[whiteastro]

Been thinking about modifying my GE CB with it's Rubber Duckie antenna with a adapter so I could change it to a BNC (?) Steel extendable Cb antenna like on other hand helds. It would be nice to be able to throw it in my motorcycle backpack or on my ATV for those mountain top excursions when I want to play. I have all the adapters for external power and CB antenna but don't want to deal with external antennas for my toys. Anyone ever do this and do you know where to get a adapter to change it to BNC (?) The male thread on the Rubber Duckie antenna looks like 5/16 but I haven't checked that out close yet either, could be metric. Haven't located too much fine detail on the radio. Hopefully some one has been down this road and willing to share. Thanks in advance and PS the radio is already bought and paid for so I don't want to buy another.