Thanks !!
The '97-'99 models used a two-screw arrangement to hold the lens in place whereas the '00-up versions and all VTX models used a single-screw/tab retainer system.
Which, coincidentally, includes the VTX1800N. It came stock with clear lenses and the newer style signals.
Get thee to eBay and buy yourself a complete set of takeoffs from an -N model or get thee into a microfiche and buy the lenses from one new...and then hunt around for a set of late model Valkyrie turn signals on which to mount the lenses. They're a direct swap for yours.
