Originally Posted by T-Mar

Actually, it's looks post boom to me, especially with those swaged, steel, cotterless cranks. The aluminum sidpull brakes, cut out cage on the front derailleur and graphics style are also typical of post boom models. I'm guessing very late 1970s or early 1980s. Regardless, there should be a two letter date code on the back of the parallelogram of the Shimano rear deraiileur. That should nail the age within a year.