With the addition of a rear suspension in 1958, The Hydra-Glide evolved into the Duo-Glide - the first non-rigid big civilian Harley in the company's 55-year history. The Duo-Glide was produced until 1965 when it was replaced by the legendary Electra Glide. All Duo-Glide models were powered by the latest version of Harley Davidson motorcycles 74" Panhead engine, first introduced in 1948.
The panhead was a Harley-Davidson motorcycle engine, so nicknamed because of the distinct shape of the rocker covers. The engine is a two-cylinder, two-valve-per-cylinder, pushrod V-twin. The engine replaced the Knucklehead engine in 1948 and was manufactured until 1965 when it was replaced by the shovelhead.