[Milsurplus] U.S. use of a PRC-174?

[Dennis]

A couple days ago I went out to get an ST-138 to strap my PRC1099 in.
When I went to blow the dust off it I notice that it was not an
ST-138(for the PRC-25/77) but instead an ST-2743/PRC-174!

The
ST-2743 has it's slightly wider shelf located closer to the bottom of
the harness than the ST-138, & it's hardware is OD rather the
black. The 2 I have appear to be unused.

My question is, I
obtained these from a source in the U.S. years ago well before the
general availability of the PRC-174. Did the U.S. government acquire
any PRC-174 for whatever reason? If so what was the reason? Did they
get used? By who?

KB0SFP
Monitor(all USB): 
3996, 5403.5, 7296, 14342.5, 18157.5S