I might be able to study the style of the lettering closely and get a better guess, but just on intuition I'd say probably late 70's or early 80's. Really not certain, though. I have had this in my collection for probably 25 years or so. Can't remember if it was a purchase or if it was given to me or what. Definitely not a recent find, though. Came across it as I was trying to get organized. Thanks everyone for taking a look.