VIN Stamp on 69/70 340 Engine

I have a 340, date stamp is 7-10-69. So I guess it could be a 69 or a 70. I am not sure what the motor was originally in, but I do know it was taken out of a 1970 Barracuda 35 years ago and replaced with a 440. Anyway, where the 6 digit VIN is stamped above the oil pan the numbers are preceeded by the Letters "OR" Does anyone know what this stands for? Thanks