Complex sentence: It was reorganised to supply diesel engine parts that were previously bought from sub-contractors, including: cylinder heads, crankcases, flywheels, gearcases and a multitude of small parts for the parent plants.
Split into simpler sentences: It was reorganised to supply diesel engine parts that were previously bought from sub-contractors. The plant produced cylinder heads, crankcases, flywheels, gearcases and a multitude of small parts for the parent plants.