Age and info about this JW Red Bottle Please

My father-in-law gave me this bottle which he has had in his basement for a long time. I suspect that it is from the early 70s but wondered if anyone could help me with determining its age. I know that Scotch doesn't age in the bottle, but wonder if it will taste different from today's JW because of a different blend. Does anyone know if the blends have changed significantly over the last decades?