SPDs are different vom plant to plant, year to year.
the thread you mention is about 1970 models.
So lets look at the other plants and what they did in the 1970 model year:
in St. Louis you have SPD 710 as the latest stamped on the tag with highest VINs in the "258xxx" range
In Hamtramck you have SPD 730 as the latest stamped on the tag with highest VINs in the "443xxx" range
In Jefferson it is SPD 717 as the latest stamped with the highest VINs in the "270xxx" range
In the Belvidere plant it is SPD 724 as the latest with highest VINs in the "312xxx" range
In the Lynch road plant it is SPD 710 with a "245xxx" VIN (but I have higher VINs in the 245 range that have SPDs of 702 and 703 !)
In Los Angeles the highest SPDs are 724 with VINs in the "161xxx" range
The Newark assembly plant is my soft spot. I do not have enough tags. Highest SPD is 616 with a VIN of "249xxx" but there will be lots more.
The windsor plant is also a soft spot. I have SPD 722 with a VIN of "344xxx" but there might be more
Every plant had there tags stamped differently. But the Hamtramck tag tells you that a few cars were probably buillt right till the end of the month. In every plant independend from what the SPD says
Carsten