[70 copo]

The focus on the VIN# alone will normally get you to the day of assembly, however the actual final assembly date could be influenced by a number of overall factors which include:

Pre-production hold at Fisher Body.
Body Bank hold at Fisher Body.
Post start production delay at Fisher Body. (set off)
Cycle bank hold at Chevrolet.
AGR Repair hold at Chevrolet.
Repair hold in the repair lot at Chevrolet.

The car was considered production complete when the car was bought out by the inspector and moved to the OK lot.(ready to ship)

Finally the VIN# has some value for assembly date estimation purposes. to be clear the "Units" as they were called = were built in assembly sequence not VIN# order.