The Assembly Manual was issued by Chevrolet Engineering Graphics as an informational aid to the assembly plants; the only difference between plants was the location of the partial VIN stamps on the engines and transmissions - see UPC6 and 7 (Norwood was a Fisher Body/Chevrolet plant, and Van Nuys was a GMAD plant, with slight differences in the Engine Dress Line processes).
There were no structural differences in the cars, but many fasteners and small parts for Van Nuys cars were sourced on the west coast, along with gas tanks; part numbers were the same as used at Norwood - they just came from different suppliers.