I live in Williamson Co. ,I know all the counties surrounding Nashville have emissions testing. But some don't. I just sold my 78 F-150 that I had for four years. I had to test it. Since 1979 was the first real year of smog pieces across the board i.e - smog pumps,cats,smaller fuel necks,unleaded fuel only in gauges.My 78 always passed with no problem. I had a 400 with Edelbrock intake and Holley carb and duals with no cat. My son's 79 Bronco we had to add a cat to the exhaust and do a lot of adjustment to make it pass. PITA !!! Hope this helps