He is talking about the VON not the last six numbers of the VIN I believe?
Some VONs do have a meaning - if it starts with a letter.
Dealerships were sent blank order pads, the VON was in the upper left hand corner of each page. I have not figured out how may pages were in each pad yet, but it was at least 25. The VON number on the order sheet was used to track the car inside the assembly plant, & for transport to its final dealership destination.
In some cases, where the VONs track a dealership can be determined if other cars known to be from the same dealership have been recorded. It is a rare thing though, because most folks do not have the original dealership data for their cars. For some dealerships that I have seen the records for, I can recognize the dealership the car went to based on the VON.
If the order for the car was "in house", like a sales bank car the VONs are fairly random.