Well...figured it out.
It's the flyback
What's weird is it reads open on the DMM, but it still kinda makes HV. I'm not sure how that works - maybe it arcs over?
Anyway, I'll have to hunt one down. So far, the Sam's lists the subs:
Stancor A-8117
Chicago TFB-1
FWIW, the Maggie # is 320026-1
Looks like a '630 one, but I'm sure they all did back then :/