Sorry your Silverado failed the smog check for missing numbers on the CAT. It's quite possible that the catalytic converter had been replaced in the past with one which is not CA complaint. We can always choose to get a second look from a different smog station.
The law in terms of emission components (in this case the catalytic converter) having an EO (executive order) number stamped and visible has not changed. Smog technicians were always required to inspect the CAT for proper numbers. The difference now is the new STAR program is ensuring technicians check every CAT, along with other smog parts, or risk losing their STAR status. For a test only center losing STAR status could been closing shop. Basically smog test centers are much stricter now.
