[Mr70]

"Using a 1968 Chevrolet as an example...is the sequence number unigue to the body style and plant or would it represent the entire car line?"
Were talkin just 1968 production here,so the answer is No,the last 6 digits were not unique to the bodystyle or plant,nor did it represent the entire carline.12 plants assembled the 1968 Passenger series & started them all at #100001.The 1968 Chevelle was also started at #100001 and assembled at the same plant as the Passenger series at their Oshawa,Ontario location.

"Could a Chevelle built in Atlanta have the exact numbering,except for plant as a similar car built at Baltimore?"
Yes,because 6 plants assembled the 1968 Chevelle.All 6 started at #100001.However one plant stopped at sequence #138705,another #166282,another #171775,etc..you can see they didn't all end at the same sequence #.

"Could the same Chevelle built in Atlanta have the exact same numbering as an Impala,except body style or group built at the same plant?"
Yes,but only at the Oshawa,Ontario assembly plant as that was the only plant that assembled both the Chevelle & the Pass. series car at the same time during 1968 and both were started at #100001.

"Using 1969 Z28 as an example is the only difference in a Camaro's Vin number going to be the plant..
Yes that's right,because both Norwood & Van Nuys started the Camaro at #500001,and that was the only car Chevrolet had being assembled at those two plants at that time.


Before 1968,all Chevrolet assembly plants started each vehicles production at the exact same sequence number at all of their respective plants,#100001.
Beginning with 1968,they started to mix it up and designated each vehicle with it's own unique sequence number at each of their respective plants..Corvettes started at #400001,Chevy II at #200001,Camaro at #300001.But the Chevelle & Pass. stuck with #100001.They started to change as the years followed.
Very few Chevrolet vehicles back then shared the same assembly plant at the same time,but there were two or three vehicles each consecutive year that did.