Ultra neck with maple fretboard - from what?
I picked up a 22-fret Ibanez neck with a maple board awhile back for a project. I'm just now getting around to putting it on something. At the time I bought it, I didn't really know what it was. Now, having looked at the codes stamped in the heel (UALML), and the old thread where Rich and Toshiro discussed the codes, I know it is an Ultra (other codes mean Angled headstock, Locknut, Maple fretboard, with Large frets). The inlays are small black dots, and the neck has the old style joint.
I recall a few mentions of 540R's with maple fretboards in the forum, and I believe there have been one or two for sale. Am I remembering correctly? I don't see those in the catalogs and was wondering what year(s) they were sold. Is that the only possibility for this neck? The only other maple board 22-fretter with locking nut I can think of is the 94-ish 540S, but they had oval inlays, AANJ, and "S-series" on the headstock.
So is the 540R the only possible source for this neck? Year?