[Milsurplus] GRC-9 questions

[Hue Miller]

Looking at some GRC-9s today:
1. what does red paint on the case, or in one set,
sprayed right on the front panel, what does that mean?
Is that how they were marked as excess?
2. The "simplified nameplate", with just 2 lines
of data, the set type and below it, "U.S." 
(no date or manufacturer), is this how AVCO
rebuilds were labeled? 
In one set I saw, the transmitter had the original
label, the receiver had the new "simplified nameplate"
but both parts had the same S/N.
3. How late were these built? Latest contract
date I see is 1956.

Tnx-  Hue Miller