what take the vin #???

[formula350]

Ok so, I have a 78 firebird non Cali car, less smog restrictions than a cali car, but none the less restricted.

Now I also have a 70, but prefer the 78 style.
So what gives the car the vin?

The frame? the body? does it even matter?

If I turned both into one car, which vin would it take?



I want to keep the 70 vin, but the 78 body, go I get the style I'm looking for, but not have to worry about smog standards.
Those can be really limiting on what I can do with the entire drivetrain?
Does anyone know about this stuff?