I built a "vin" number decoder that can be found here:
The VIN Cruncher It will presently decode the serial numbers for Chevrolet Trucks from 1929 thru 1956.. just enter the code with ALL CAPS and remove any dashes.
Your 14RJC1439 comes up as:
Year: 1949
Type: 1.5 ton
WB: 137
Plant: Baltimore, MD
Month: March
The character in the "C" position indicates the month of production, i.e. A=Jan B=Feb C=Mar so it's definately not an "O".