The S-Type was a major redevelopment of the Mark 2. It used a mid-scale version of the Mark X independent rear suspension to replace the Mark 2's live rear axle and featured longer rear bodywork, among other styling and interior changes. The S-Type was available with either 3.4 or 3.8-litre XK engines but only in twin carburettor form because the triple carburettor setup would not fit into what was essentially still the Mark 2 engine bay.