Hey Gordon, thanks for the response.
I have what looks like a GL1200 antenna that came with the bike, but like most things the PO did, it's messed up and won't attach correctly.
I've got the OEM Valk mount, but need a new antenna.
Reading the post by BonS and Kingbee, it looks like I'll need to modify a new/used GL1200 one.
Do you know what needs to be done?