I need Help

I have seen this sweet looking Grand Prix around my neighborhood but I cant figure out what year it is. I have narrowed it down to a 70's model and I think an earlier one, the hood has a more noticable arrow like design. I was wondering if anyone could tell me some noticable differences in each year produced for the 70's so next time I see it I can figure out what year it is. Any help possible would be appreciated.