Had to do the annual Arizona emissions test this week, truck passed fine but 2 of the techs spent a few minutes looking at the front of the engine block area. I asked what they were looking for and they would not tell me. They said I would need to go inside and ask. Well, after already giving up almost an hour of time just to get test results I was ready to go. Any ideas?

 

The manufacturer's sticker that states the spark plug gap?

ETA:.... Maybe they were looking for the "G" in Cummins.

 

Maybe looking for a little black box??

 

Probably looking for endangered species stuck under the engine.

Or maybe a sticker like this one: