Anyone have one of these they aren't using? I know of only I think 2 or 3 in existence, so this is definitely needle-in-the-haystack level request, but hey, guess you never know unless you ask! One of them was a prototype they put on a single valve bass rotor which I'm not sure they ever even sold because they said it played very flat... and that was going on over a decade ago at this point.

Edit: To clarify, tuning slide would go in a bass valve section and attach it to a tenor bell.