In August 1979, for the 1980 model year, AMC introduced four-wheel drive versions of the Spirit and Concord, calling the collective line the AMC Eagle. Eagles rapidly became one of the company's best-known products and is considered one of the first "crossover SUVs". Eagles used the 2-wheel drive body shells mounted on an all-new platform developed by American Motors in the late 1970s. Featuring an innovative full-time four-wheel drive system, it sold best in snow-prone areas. Sales started strongly but declined over time. While the two-wheel drive Spirit and Concord were both discontinued after 1983 as the company concentrated on its new Renault Alliance, the Eagle survived for five years longer, albeit only in station wagon form, into the 1988 model year. This meant the four-wheel drive Eagle was the lone representative of the AMC brand from 1984–1988. All the company's remaining output was branded Renault or Jeep. The last AMC Eagle was built on December 14, 1987.