I've got a suspicion that the Grizzly G9972Z spindle thread may not
be 1.75x8

I bought a Kalamazoo Chuck Micro Set chuck and a 1.75x8 mounting
plate. The plate screws on about 4 threads, then stops. It does this
from either direction. My suspicions are that I'm dealing with a metric
thread.

Anyone have a seller of M45x3 nuts so I can check the spindle nose?
There are NO points for Grainger or McMaster.