For the 1977 model year, the Ferrari 308 continued in production but it was switched to use a steel body instead of the fiberglass body (Vetroresina) that it had been launched with. This resulted in an overall weight increase of approximately 150 kg (331 lb). The same year, the GTS version was launched as well. In 1980, after approximately 2,897 GTB's had been produced, the 308 would evolve into the fuel injected Ferrari 308 GTBi, although sales of the carbureted version would continue into 1981 in select markets.