The GM A platform (1936) (commonly called A-body) was a rear wheel drive automobile platform designation used by General Motors from at least 1936 until 1959, and again from 1964 to 1981. In 1982, GM introduced a new front wheel drive A platform, and existing intermediate rear wheel drive products were redesignated as G-bodies.
The earliest GM A-bodied based cars shared a common platform with the Chevrolet Superior, with Pontiac replacing Oakland during the early 1930s. Oldsmobile also used the A-body for the 1936-39 Oldsmobile Series F and 1940-48 Series 60. All Chevrolets produced during this period, to include the Chevrolet Master and the Chevrolet Deluxe, and all 1936-39 Pontiacs, the 1940 Pontiac Special, the 1941 Pontiac Deluxe Torpedo and all Pontiac Torpedoes produced from 1942 through 1948 were A-bodies.
From 1949 to 1957, only Chevrolets (150, 210, Bel Air, Del Ray, Biscayne, and Impala), Pontiacs (Chieftain, Star Chief, Super Chief, Bonneville), and Oldsmobile models 76 and 88 in 1949 and 1950 and Oldsmobile 88-A in 1951, were built on the A-body. These cars were moved to the new B Body shared with some Buicks and Oldsmobiles in 1958, and all truck conversions were replaced by the C/K series in 1960.
The A-body platform was reintroduced as an intermediate-sized platform introduced in the 1964 model year for the all-new mid-sized cars of four GM divisions. Notable examples include the FR layout Chevrolet Chevelle, Buick Special, Oldsmobile Cutlass and Pontiac Tempest. The A-body cars were the first intermediate-sized cars designed with a full perimeter frame and four-link coil-spring rear suspension, similar to that introduced on full-sized Pontiacs and Oldsmobiles in 1961 and on all other GM full-sized cars in 1965.
The Chevrolet A-body line included the El Camino coupe utility. Two station wagons based on the A-body used stretched wheelbases and raised rear roof sections with skylights: the 1964–1972 Oldsmobile Vista Cruiser and the 1964–69 Buick Sport Wagon.
All A-body cars had a 115 in (290 cm) wheelbase except the stretched-wheelbase wagons, which had a 120 in (300 cm) wheelbase.
Some of GM's most successful products in the muscle car era were A-body models, including the Pontiac GTO, Chevrolet Malibu SS, Oldsmobile 442 and Buick GS. From 1964 to 1969, GM Canada produced a special-market version of the Chevelle called the Beaumont, which included Pontiac-type trim and unique front grilles as well as taillight assemblies.
When the A-body cars were introduced in 1964, GM had set a corporate policy prohibiting V8 engines larger than 330 cu in (5.4 L) in these models. However, Pontiac fitted its 389 cu in (6.37 L) V8 in the Lemans to create the GTO — commonly considered the first popular muscle car. Though this violated the 330 cu in limit, Pontiac got around the rules by designating the GTO as a low-volume option package rather than a specific model. The sales success of the 1964 GTO led the corporation to increase the cubic inch limit for 1965 A-body cars to 400 cu in (6.6 L), opening the door for the other three divisions to offer similar muscle cars. The 400 cu in limit for A-body cars, as well as for other GM cars that were smaller than full-sized (with the exception of the Chevrolet Corvette), was continued through the 1969 model year.
All GM A-bodies were completely restyled in 1968. The 400 cu in limit remained. In 1970 the 400 cu in limit was removed, mainly due to Chrysler's domination in the drag racing and muscle car market with larger engines and highest power rated engines available in nearly all Chrysler "B" platform models. This led each of the four GM divisions to offer their largest engines: Chevrolet's 454 cu in (7.44 L) in the Chevelle SS-454, Pontiac's 455 cu in (7.46 L) in the GTO, Oldsmobile's 455 cu in (7.46 L) in the 442, and Buick's 455 cu in (7.46 L) in the GS.
The two-door had a 112 in (280 cm) wheelbase; four-door, station wagon, and the El Camino had a 116 in (290 cm) wheelbase; and the stretched-wheelbase wagon had a 121 in (310 cm) wheelbase. 1968 model year A-body 2-door hardtops and convertibles had a vent wing window assembly - 1969-72 models had a one piece door glass where GM's Astro Ventilation system (first used with the 1966 Buick Riviera) was phased in.
Also using a variation of the A-body chassis and suspension were the 1969-1972 Pontiac Grand Prix and 1970-1972 Chevrolet Monte Carlo — both of which were marketed as intermediate-sized personal luxury cars and coded as G-body cars. The Grand Prix had a 118 in (300 cm) wheelbase and the Monte Carlo had a 116 in (290 cm) wheelbase. When the A- and G-body cars were restyled for 1973, the G-body design was renamed the A-special body.
All GM A- and A-special body cars were completely restyled for 1973 with hardtop and convertible bodystyles completely eliminated due to pending Federal safety regulations. The 1973-77 cars were available in sedans, coupes and station wagons. General Motors described the pillared bodystyles with frameless doors and windows as "Colonnade" styling. Wheelbases for this generation were 112 for two-door coupes and 116 for four-door sedans and wagons.
By this time, the American performance car was considered extinct, but these "forgotten years" had some performance left.
All GM intermediate-sized cars were downsized for the 1978 model year in response to CAFE requirements and the increased popularity of smaller cars. The redesigned models were similar in size to the previous X-bodies.
The Buick and Oldsmobile were introduced with fastback coupe styles, while the Chevrolet and Pontiac received notchbacks. Four-door fastback sedan models were also available. An interesting design compromise was non-lowering rear door windows on four-door sedans and wagons, which also reverted to full window frames while two-door models including the El Camino retained frameless glass. Performance applications included the Chevrolet Malibu F41 and M80, Pontiac LeMans GT, Oldsmobile 442 and Oldsmobile Hurst/Olds.
In 1982, with the introduction of the new front-wheel drive A-body, existing rear-wheel drive models were given the G-body designation.
Models of this generation include: