built 3,969 of these models and most came with automatic transmissions. Duster 360 options included Goodyear raised white letter tires on rally wheels. Air conditioning, fold-back sunroof, and flip-down rear seat were also available. 1975 The 1975 models were mostly unchanged from the previous two years, with some exceptions: a new grille with a return of the Plymouth 3-pointed-'spear' affixed to the grille's center; catalytic converters were added to 225 Slant Six and 318 V8 models (the 360 was not equipped with a converter and its power was now , due to the addition of a secondary air injection system, commonly referred to as a "smog pump". Fewer than 2000 of the 1975 model Dusters left the factory equipped with the 360 engine. 1976 The grille-mounted park and turn signal lenses were amber; prior years had colorless lenses with amber bulbs. The interior rearview mirror was mounted directly to the windshield rather than to the previous double-pivot roof bracket, and the parking brake was now foot- rather than hand-operated. Disc brakes became standard equipment on cars built after 1 January 1976. Several special models were offered: The Feather Duster featured lightweight aluminum parts including the intake manifold, bumper brackets, hood and trunk bracing, and manual transmission housing, for a weight savings of about —5% lighter than a standard Duster similarly equipped. It came with a 225 Slant Six with its distributor and single-barrel carburetor calibrated for economy, a low-restriction exhaust system, an extra-high rear axle ratio, and was offered with either the Torqueflite 3-speed automatic or A833 overdrive 4-speed manual transmission. It was the most fuel-efficient car in its size class, achieving up to 36 mpg highway and 24 in the city with the manual transmission option (along with Dodge's version, the Dart Lite). The Space Duster had fold-down rear seat and security panel and combined with the luggage compartment, offered over . of cargo space. (This feature was actually introduced, optionally, in 1973). The Silver Duster had special stripes and a cloth Boca Raton style interior. The Duster 360 option was deleted as a separate model as the engine became an option on any trim level Duster, and about 1,300 cars were equipped with it. The 1976 360-powered Duster (and Dart Sport 360) was still without a catalytic converter, and while its power was down to , the car could still manage 0-60 mph in 7.9 seconds when equipped