Congrats!
According to the Sears catalog, that color was called "Sour Apple Green". Yours appears to be a 1976, 1977 model of this canister. There was a earlier 1974, 1975 variation that had a shorter hose, and a Green non detachable painted wand on the power head, unlike your chrome, removable two piece wand. excellent canister! Enjoy it!
Phillip.