and DeVille models. The most dramatic of these changes was the addition of rectangular headlamps in 1975 along with a completely new grille. This configuration was carried through until 1977's dramatic downsizing, marking the temporary end of all full-size Cadillacs except for the Eldorado. For 1971, the lineup was trimmed down to just one Sixty Special model, the Sixty Special Brougham. It still rode on an exclusive wheelbase, but with all-new sheet metal and a distinctive roof design. The formal new roof was clearly reminiscent of Bill Mitchell's original 1938 Sixty Special, with individually framed, rounded-corner side glass (outlined by a thin chrome bead). Also new on the vinyl top were C-pillar mounted opera lamps and a thick B-pillar, which, along with a narrow body filler panel between the front and rear side doors, heightened the car's custom limousine look. Despite the formal new look and higher levels of luxury, sales dropped slightly from 1970, down to 15,200 units. As before, while the coupe and sedan DeVille remained Cadillac's bread-and-butter cars, the Sixty Special was an exclusive low-volume item sold to its most affluent buyers and the fleet and livery business for conversion to formal limousines and airport cars. Engine performance began to decrease with EPA restrictions on tailpipe emissions and grams per mile emissions requirements, forcing gear ratios to taller and taller ratios, dropping to as low as 2.73:1 for 1975–1976. A new common frame/suspension design was introduced in the latest generation Sixty Special which was also used in other GM full size cars. While the other GM divisions used a front-steer setup (steering linkage in front of the engine crossmember), all Cadillac RWDs retained the 1961-vintage front suspension (rear steering linkage, eccentric cams in the steering knuckle in lieu of shims, strut rods attached to the framerails for caster adjustment). Rear suspensions were now driven by the Pontiac-designed -inch ring-gear 10-bolt Salisbury live axle. A new trailer towing package was added allowing larger trailer loads to be pulled. Coupled with heavy duty cooling, 3.23 gearing, high output 80 amp large frame alternator and heavy-duty THM400 transmission, the long wheelbase was ideal to pull trailers weighing up to 7,000 lb (3,200 kg). 1972 marked Cadillac's 70th anniversary. One of the few changes that year was the addition of a chrome molding around the rear window. Sales were a robust 20,750 units at a base price of $7,585. The 1972