[DeadheadNM]

That photo was from a CL ad and is all I have and was on a C20 if I recall. It’s possible this decal is specific to 3/4t pickups but I can’t confirm that. Given that at least some passenger cars received these too it’s possible that 1/2t trucks did as well (or one that’s similar). Note the decal references “California Heavy Duty Standard” for what that’s worth.

Here’s a reproduction of a WA code decal designed for use on a Chevelle or Corvette. Cheap copy that isn’t an inner glass decal but could serve as template of sorts. It’s possible that other year passenger car reproductions may be truer to the WK example used for trucks.

I do have reproductions of the CA emissions specific LM code tuning decal that’s affixed to the inner fender under the hood. These are the only reproductions in existence but are for use on 350 equipped 1/2t pickups/K5s and I suspect 3/4t suburbans.