Some of these are +/- 1 G and others are +/- 2 G units.
They are covered by patents:
3057195 Force Measuring System, Oct. 9, 1962
3074279 Position Detecting Transducer, Jan. 22 1963
This SD unit looks very much like the Jewel
Maybe SD sold this line to them.
It would make sense because the patents show a mechanical mechanism that looks very much like a meter movement.
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