F5000 and F3000

F5000 (Formula 5000) was a single seater catregory that evolved in the USA in 1968 and used 5 litre stock block engines. The UK  adopted the category in 1968 and it ran until 1977/78.  F3000 (Formula 3000) ran from 1985 until 2004 and used 3 litre engines.