They built Tbirds at the Milpitas plant, my wife worked at that mall many years ago. There was a little area that had some facts about the plant and maybe a tbird? or just a picture of one, its been a long time. Anyways, DSO is the district sales office and represents an area of dealers. I'm pretty sure the dealers would send orders in to be processed by Ford to the DSO. Vin #11 is the assembly plant.
A - Atlanta
B - Oakville
F - Dearborn
G - Chicago
H - Lorain
K - Kansas City
T - Edison
W - Wayne
X - St. Thomas
Y - Wixom
R - Hermosillo, Mexico
U - Louisville
V - Jefferson county
8 - Broadsmeadows, Australia
My 1990 Lincoln Mark VII has a 72 DSO (san jose) as the car was sold somewhere in the bay area. But the car was built at the Wixom plant.
Edit:
I did some googling and found this info
"As noted, the San Jose Plant was closed by Ford Motor Company on May 20, 1983, after having assembled a total of 2,660,665 vehicles there – the final car built on the last day of production was a bright red Ford Escort 3-door hatchback "
Also I am wrong about the Tbirds, It must have been a 1st gen mustang i remember?