Does anyone know what specific units this rack was meant to hold? Mike, W6MAB http://www.ebay.com/itm/RADIO-RACK-ARC-E-17-GOLD-PLATED-PINS-OLD-ANTIQUE-AIRCRAFT-AVIONIC-PART-/251052424090?pt=Motors_Aviation_Parts_Gear&hash=item3a73e3fb9a&vxp=mtr