Nevertheless, the new guide nut is a lot sturdier looking than the original, and the previous replacement nut. No high-shine chrome, no sexy inscribed ring, and especially no extra set of holes!
Before installation this time, I also put all the washers on the axle and tightened the nut all the way down and MEASURED THE GAP. It was 1mm wider than the thickness of my dropout. Oh.
The gap on the left side was small enough to get tight, but the drive-side nut wouldn’t be able to tighten down all the way. Bear in mind that this is a different axle and internal mechanism than the one I broke the first guide nut on, so I’d measure before installation on any bike. Measure the dropout width, measure the gap left after tightening all the nuts and washers up finger-tight. If the gap is bigger than the dropout, add a washer.
David did say that adding an extra washer would NOT mess up the shifting the same way using a long (AW-sized) guide nut would.
I added the washer, and the wheel seems tight, and the shifter shifts fine. I rode the bike a few miles, and I’ll adjust the cones tomorrow and ride it some more.