For the 1966 season, Ferrari built a new series of 12 lightweight 275 GTB/C racing cars. Even though they outwardly resembled the road-going 275 GTB, the 275 GTB/C was thoroughly revised by Mauro Forghieri and his Scuderia Ferrari engineering team and differed from both the 275 GTB production car and earlier 275 GTB competition cars. Every panel of the body was altered and substantial mechanical changes were made. All 12 were constructed in 1966 between the end of the 275 GTB (two cam) production run and the start of the 275 GTB/4 (four cam) production run.