The common misconception about this next ad is that Crazy Eddie, a now-defunct regional chain of stores in New York City and its surrounding environs, hired members of Sha Na Na to appear in the ad. Not even close.
The success of the movie, "The Lords of Flatbush", had a lot to do with this ad being made. Yes, doo-wop was making a bit of a comeback, as part of the 50's nostalgia wave that really got kickin' with the launch of Happy Days earlier in 1974. Jeff Goldschalk is the lead vocalist of this group.
A few years later, General Mills got in on the doo-wop act to promote a short-lived cereal. Donutz lasted a couple of years, but General Mills' ad agency opted for a quartet of doo-woppin' donuts to sell the product. We'll have that over at Saturday Morning Archives real soon.