Take a look at the RAX receiver at:
http://www.ebay.com/itm/161095441386
There's a red stamping under the nomenclature plate.
I can make out:
MODIFIED FOR OPERATIONAL
FLIGHT ( sumthin' sumthin' sumthin)
DO NOT INSTALL
IN AIRCRAFT
Can someone with a Hi-Def display make out
the words after "FLIGHT" ?