Aren't the (from 68 vs 69)
a) Spoiler studs changed, 68 Lacks flange changed to flanged 69
b)Disc Brakes Calipers & associated, 4 piston upgraded (?) to single piston
c) Power Booster Markings (DELCO STAMP) Lack of in 68 and applied in 69
d) Voltage regulator mounting method, 68 insulator well nut and ground wire changed to solid screws in 69
not sure if these thoughts are helpful?
JIM