Judging from the literature, it looks like early 80s... The brochure has a "Chevy Power" logo in it that i think was used in about 1982 or so... I'm really not positive on specifics though. as for the 2 styles of Yenko wording on the blocks, I'm not sure if that was a "early/late" thing, or if one style may be a tall deck block, and one a standard... they made both types. The version with the Yenko logo is definitely the cooler looking design of the 2!
