For 1970

CHALLENGER
N95 - Evaporative Control System - required on all cars registered in the State of California N.A. otherwise .......... $37.85
N97 - Noise Reduction Package - required on all cars registered in the state of California equipped with 440-6 engines or 426 Hemi .......... N.C.

CHARGER
N42 - EXHAUST Bright Tips (N.A. California) R/T only .......... $20.80
N95 - Evaporative Control System - required on all cars registered in the State of California N.A. otherwise .......... $37.85
N97 - Noise Reduction Package - required on all cars registered in the state of California equipped with 383-4 or 440 engines .......... N.C.

CORONET
N42 - EXHAUST Bright Tips (N.A. California) Super Bee & R/T only .......... $20.80
N95 - Evaporative Control System - required on all cars registered in the State of California N.A. otherwise .......... $37.85
N97 - Noise Reduction Package - required on all cars registered in the state of California equipped with 383-4 or 440 engines .......... N.C.

DART
N95 - Evaporative Control System - required on all cars registered in the State of California N.A. otherwise .......... $37.85

POLARA & MONACO
N95 - Evaporative Control System - required on all cars registered in the State of California N.A. otherwise .......... $37.85

This info is taken trom the 1970 Dodge Pocket Salesman's Guide posted on Hamtramck Historical.
Does anyone have the '70 PLYMOUTH version? It would be great to see it posted also.

Although not written in stone, here's my take:
N95 - for any car destined to be "SOLD" new in California, I'm sure some cars with N95 were SOLD new in other states due to dealer trades & sales bank cars that were not in demand in California. Any ordered car that was delivered NEW in the State of California should have N95. N95 concerned the fuel system: fuel tank venting, gas caps, carburetors, etc..

N97 - Noise reduction was accieved in different ways on different body platforms, again California "only".
E-body - eliminate N42 "bright exhaust tips" from 440-6 & Hemi cars.
B-body - addition of resonators on 383-4 & 440 cars. These are the same resonators found "stock" on Hemi cars.

N42 - According to the "pocket guide" none for California in:
440-6 & Hemi Challenger R/Ts
383-4, 440-6 & Hemi Super Bees
440-4, 440-6 & Hemi Charger R/Ts & Coronet R/Ts

BUT

There are exceptions, I own a LA assembled 440-6 4-spd GTX; fender tag reads: N41 N42 N85 N95 N96 N97 or is that a Plymouth thing?