70 340 Block

I don't think that the assembly plant sequence number is coded on the fender tag...

They are on the broadcast sheets/build sheets that you usually find under a seat or behind the glove box.... There is a space on the build sheet that lists the assembly plant sequence number...
I guess the fender tag shows the order number and options, but not a lot else other than order number and the V.I.N. then.
So, without a broadcast sheet, you can't tell if the cars were actually built back to back, right?