1961 Plymouth Belvedere: Starting in 1960, Belvederes got a brand-new standard inline six-cylinder engine. Colloquially known as the slant-6, it displaced 225 cu in (3.69 l), featured overhead valves, and a block that was inclined 30 degrees to the right to permit a lower hood line with maximum displacement. This engine used a single-barrel Holley carburetor, and became known for its extremely rugged construction, exceptional reliability and longevity. In 1961, "most beholders would agree...it was hit with the ugly stick."
Source: Wikipedia, 2013