I have a what visually is a Candy Yellow Special CT70K1. The black tag on the steering neck reads 9/71 and the frame VIN is CT70-2013XXX. Everything I've read indicates it is a 1972. However, the engine VIN is CT70E-213XXX. I'm the fourth owner and I know owners two and three and they have not done any major modification other than regular maintenance dating back to probably the early 90's. The California Title says that is a 1973 model year. Any insight why it would be listed as a 1973?