It should be noted that this information pertains to Chevelles only. Other Chevrolet lines (Camaro, Nova, etc.) and their plants may differ. For example, a 1969 full size car with a 350 V8 from Van Nuys has been reported with the partial VIN on the oil filter boss and other Chevrolet models and/or plants may exhibit the same properties. 

Sample of Baltimore stamping on engine pad.

Sample of Framingham stamping on engine pad.

Research indicates that the Atlanta & Kansas City plants used this alternate location for 396 engines. This is a partial VIN stamping from Kansas City.

Atlanta 396 partial VIN stamping.

Atlanta 396 partial VIN stamping.