My son is in the Navy stationed in San Diego. The base told him he needed the 92 CTD smogged to get stickers. Being the good citizen he is he went down to testing station, after a little detuning, to get the certification. The tech drives it in and walks back out and says "this is a diesel, we don't smog diesels in California" and sent him on his way. Now it may be a local deal to smog check diesels but it sure ain't something required at the state level and we GOT that in WRITING!
Here in the Treasure Valley around Boise and Meridian, Ada county requires smog checks on all vehicles. Canyon county, right next door, does not require it and cannot get the citizens to approve it. Check your local codes as it may be required in problem areas.