An “S” should be present on the cowl or after the registration number on World War Two jeeps. It went on the jeeps that passed the radio interference test whether or not they had a radio. AR 850-5, Change 9, dated 27 Jan 1944, a regulation that required an “S” marked on vehicles. This same change also stated an “S” marked vehicle was to be preferred over a non-S marked vehicle when installing a radio. Common sense? Well, sometimes the Army had to spell it out.CRW_3615_adj2xzx_blue‘S’ symbol on the cowl of a 1942 Ford GPW and Army Jill sitting on the fender.

CU_USN_jeepAn interesting closeup from a photo of a US Navy jeep in use with the US Marines… This is clearly marked as a US Navy vehicle.

USN 24467

It appears that the original US Army marking and registration number was painted over with a dark olive drab or black before the yellow US Navy markings were added. Also note, the “S” to the left on the cowl. This is blue drab! The “S” was used to designate vehicles that had been tested and passed for radio suppression. This was equipment/parts added to the vehicle to help keep it from interfering with radios by eliminating static. You can also spot what may be blue drab to the right of the registration number. Also, note the dark area immediately next to the USN and registration number.