Question on Van Nuys LS6 with NA9

[SS427]

Does anyone have an original Van Nuys 70 LS6 NA9 equipped Chevelle with the original radiator top plate or a copy of the build sheet (VIN is not important to me) as I am trying to determine what tune up decal code was correct on a January Van Nuys LS6 with NA9. Every VN build sheet I have shows a DT code in that time span with AZ coming much later but this car is very original and has an AZ decal. Coincidently, all of the build sheets I have are for non NA9 cars so I am wondering if that is what makes the difference. Any help is much appreciated.

[jeffschevelle]

Was NA9 available as an "option" all year? Or did it become part of standard equipment at some point? I see where the equipment / options brochure says NA9 (Evaporative Emission Control) was "released to conform with CA registration requirements". Maybe that created the need for the AZ decal, and then later Van Nuys cars had the same equipment without showing NA9, so all got AZ decals??

[SS427]

I have two other NA9 cars in my database that are early February cars but neither has enough information to show what coded decal they had but both these cars are real so I know that the option was at least offered back to February in addition to my January car.