After falling asleep behind the wheel after a long couple days at work...I totaled my car and now knows what it feels like to be inside a dryer. So since I'm in the market for a new ride I've been thinking about getting that diesel truck I've always wanted. But I had a few questions before I start my search. 1.) I'm thinking about going used so should I buy pre Ultra Low Sulfer regulations or post? I heard that new all new diesels have to be smogged. Also any performance differences between the old and new? 2.) I know that diesels are built stouter than gas, so what is a reasonable age and mileage for a used diesel. I see a few on CL that are 2003-4, that have 130k-150k on the odometer. IF it helps I'm leaning toward Chevy/GMC duramax.