CA implemented the first emission control laws beginning in 1966. I have a 66 Rambler which sold new in CA and has an air injection pump on it. There was a requirement beginning in 1966 to install emission control devices which included crankcase ventilation systems and the carb had to be calibrated for emissions I think. I'm not sure about the carb, but there was a requirement for compliance sticker under the hood when the emissions mods were made. I think cars and light trucks imported into California had to conform for a few years. Now they don't since Federal standards have become stricter anyway. So that sticker on your windshield could have stated that the truck has beem modified to conform or that it had been exempted for some reason like 60 Anglia said. Joe