The American-based international automotive conglomerate General Motors (GM) underpins its many vehicle models with various platforms. These platforms are established sets of axles, suspensions, and steering mechanisms which fit various bodies and powertrains from various marques that GM owns. From the early twentieth century, a Latin letter-based naming scheme was used to designate platforms, which were aimed at vehicles under different brands that served similar niches of the market. For example, the B platform was the base for fullsize, rear-wheel drive (RWD) sedans and wagons from 1926 to 1996. This platform underpinned vehicles made by Buick, Cadillac, Chevrolet, Marquette, Pontiac, and Oldsmobile. During the 1970s and 1980s, GM introduced many new front-wheel drive (FWD) platforms for the first time, such as the FWD C platform introduced in 1985. Despite being mechanically very new and different, it kept the same name as the RWD C platform for the sake of consistency, as most of the models remained the same, such as the Oldsmobile 98. For most of these platforms, the platform name is the fourth character of a vehicle's VIN, with a notable exception being trucks, for which it is the fifth character. At the outset of the twenty-first century, General Motors' approach to platforms changed, and so did the nomenclature they use. Platforms themselves are now referred to by GM as "architectures", and are now named according to the English-language names of letters from the Greek alphabet, such as the subcompact Gamma platform. Today, many of the since-discontinued Latin letter platforms are informally called "bodies", such as "J-body", which refers to the J platform. In the 2010s, GM once again began to change platform nomenclature, this time to a four-character format: platform-generation-XX. An example of this is the D2XX, from the second generation of the Delta platform, hence the "D" and "2". All but three platforms listed here use a front-mounted engine, and those exceptions are noted in the 'layout' column. In production As of April 2020, GM produces cars, trucks, and sport utility vehicles (SUVs) of multiple different sizes on 19 different platforms: 7 of which are inherently RWD, with the rest being FWD. All but 5 of these have four-wheel drive variants as well. The GM nomenclature works as follows: 1st position is the platform: A – Alpha C – Chi D – Delta G – Gamma E – Epsilon P – Premium Epsilon (XTS) Y – Corvette