[Milsurplus] CR-1A/AR crystals ?

[Hubert Miller]

Found a bunch of crystals CR-1A/AR, in the range 6922.22 - 7133.33 kc/s.
What radios were these for?
One is stamped,
INSP.  7-57
REINSP. 7-59
T.O. 12-1-19

So what is this T.O. about ?
tnx-
Hue
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