As far as the stolen license plate matter, the smog technician will enter this information into the smog machine off of your vehicle registration notice.
Your 2001 Toyota Tundra's NO problem may be due to a few different things. You want to first make sure your Toyota Tundra is not running lean (CO is within average limits). Low Co may indicate a lean fuel mixture. A lean fuel mixture will cause your Tundra's engine to run hot. The heat will cause high NOx. NO is created when engine internal temperatures reach above 2500f. So look into thinks which would cause lean fuel conditions; first the oxygen sensors, the mass air flow sensor, vacuum leaks (brittle/broken vacuum lines), sticking closed fuel injectors.
If you find that all emissions systems are functioning properly, you can suspect the CAT. Your Toyota Tundra's catalytic converter (after the air/fuel mixture is corrected) takes all the NO reduction load. A defective or worn CAT will not reduce NO enough to pass a smog check.
