During final testing at the klipsch factory sometimes it is found that a particular speaker performs especially well with a certain style of music. The tester may put a code on the lable indicating their findings.
In the past I have seen on labels
RB..rhythm & blues
HR..hard rock
BG..bluegrass
Could RV be "rap voiced"?
@coyote is always looking for DM which we all know stands for Donny & Marie
Don't try to weld over the stripped threads.
That much heat could destroy that end of the horn.
I would bore that end out to 1.500 to 1.501, make a sleeve with 1.500 od x 1-3/8-18 id and press it in using sleeve adhesive.