Downsized two years after its main rivals, the Chevrolet Impala and Caprice, the 1979 LTD was fifteen inches shorter than the 1978 model (and ten inches shorter than the "mid-size" LTD II). However, the interior remained just as large as the previous LTD, and the whole design became more efficient. The reduced size and weight led to improved road manners and maneuverability, with ride quality and fuel economy improving as well. The two base engines, the 302 and 351 Windsor V8s, were carried over from 1978; the big-block 400 and 460 V8s were discontinued. For 1981 and 1982, to further improve fuel economy (while avoiding diesel or 6-cylinder engines), Ford introduced a 255 cu in (4.2 L) variant of the Windsor V8. The 255 proved an unreliable and unpopular choice; at 115 hp, its output was ill-suited for the LTD's two-ton curb weight.
Source: Wikipedia, 2013