GE had some units like that also that had a temp switch in the pilot
flame that broke the circuit to the gas valve if it wasn't red hot.
Carrier and it's other companies-- Payne, Bryant and Day&Night-- had
one that did the same thing, but was all one assembly, whereas the GE
had the same pilot burner as the 100% cutoff, and the switch screwed
into it with the same threads as a thermocouple. They were referred to
as 90% cutoff. Both were made until around the early 70's. A few other
brands used variations of the same setup eons ago. All were for NG only,
no LP. Why they used such a thing I have no idea. It really doesn't look
like it would have been any cheaper at all, and if it indeed was, it
couldn't have been enough to justify the safety issue Larry.