50th Anniversary Shelby Cobra 427 The 50-year anniversary of the iconic Shelby Cobra 427 is upon us. That means Shelby is producing a limited run of Anniversary Cobras. Engine options range from 400 horsepower up to the legendary 427 big-block that boasts a toupee-peeling 700 horses. Offered with either aluminum or fiberglass bodies. Limited to 50 Cobras.