As per Tim, 482 was the model code for the majority of the "classic" orange AG175 from the 70's. The early models just had "YAMAHA" in black lettering on the tank and the last orange models has "AG" in white above the Yamaha and had a white strip, like a giant NIKE Swoosh on the tank.
Also, the later models, post 1975, were fitted with compliance plates which will give you the month/year of manufacture. I have had a couple of AG175's and currently have one of the late 1979 models (11/79 compliance), which was the last orange model before they went to the red paint job and cross-over exhaust, and I am hopefull of getting annother early model from a farm clearance sale next Friday.
CJ
AGies are a weekness of mine!