In 1974, the US federal 5 mph (8.0 km/h) bumper impact standards were expanded to cover rear bumpers as well as front ones, and as a result the Swinger and Dart sedan's rear bumpers grew much more massive. Taillights larger than the previous year's items were set above the rear bumper, rather than within it. Shoulder and lap belts were finally combined in all Chrysler products into a retractable, inertia-sensitive, single-buckle design Chrysler called "Unibelt", replacing the difficult-to-use separate lap and shoulder belts that had been installed through 1973.
The Dart and its Plymouth Valiant sibling led the American compact car market during the early 1970s. Their already-strong popularity was bolstered by the Arab oil embargo of 1973, which caused gasoline shortages with long lines at stations and dramatic price increases at the pump. To capitalize on an emerging trend toward luxurious compact cars, Dodge introduced the Dart SE (Special Edition) in mid-1974 as a four-door sedan and two-door hardtop. The SE included velour high back bucket seats with folding armrest, carpeted door panels, woodgrain instrument panel and deluxe wheel covers along with a TorqueFlite automatic transmission as standard equipment. The Special Edition (SE) came equipped with the "Quiet Car" package introduced in 1973. The air conditioning system available on all Darts had increased capacity, quicker cooldown and lower minimum temperatures. An evaporator pressure regulator valve, long used on larger Chrysler products, varied the compressor's capacity without cycling the clutch.
The Dart Sport 340 was replaced by the Dart Sport 360 as the 360 cu in (5.9 L) V8 engine replaced the 340 cu in (5.6 L) engine discontinued after 1973.
Source: Wikipedia, 2012