Found this while googling .... very interesting and I think still mostly current. Great section on contract air services [EX: Hawker Hunters]
If link doesn't work, just google: common air frequencies 337.225
www.vacapes.navy.mil/inc/cmodules/dms/download-rel.php?secid=19&id=0&filesystem_id=4392
JohnFB
Franklin Co. - Western Massachusetts - USA