OTTO Engine Assembly 6SD1 for the Hitachi EX300-5 excavator (Isuzu 6SD1) - supplied as a complete engine assembly, ready to fit. It replaces the original engine in one go - block, cylinder head, injection system, manifolds, fan and flywheel housing - so the old engine is lifted out and the new one dropped in. Send us the machine serial and the number on your old unit and we will confirm before dispatch. 3-12 months warranty options.