[north]

Some observations:

No duplicate Pattern DON's from same zone even regardless of plant of assembly.

Regular DON's from each zone seem to follow a regular sequential pattern as the year progresses regardless of which plant the car was built in.

Interesting how most zones up with regular DON's just under 100,000 at the end of the run but they seem to start at a different number from each other. I wonder if it is because they adjusted the starting number so that the target number for each zone manager was 100,000?

Apart from the pattern cars the regular zone versus dealer (Z versus P in the invoice number prefix) ordered cars seemed to follow the regular sequential order of DON's

If you guesstimate the total number of DON's (say 75,000 times 28 zones you get an odd number, a bit over 2,100,000. I say odd because the number is way too high to be just Pontiac (about 870,000 cars that year) but way too low to be all GM cars (which were about 5,000,000 that year). Hmmm.