The Cummins ISC is a straight-six diesel engine with a displacement of 8.3 litres (506.5 cu in). Cummins began producing the engines in 1998. The engine was built off its predecessor, the Cummins C 8.3 litre engine originally introduced in 1985 as the 6C8.3 (this was co-designed with the Case Corporation, along with the smaller 6B5.9).