If you specifically require a 6-cylinder manual, these models are the common counterparts to the 4H series: 6HK1 / 4HK1 Service Manual
Because you have six cylinders, the manual will detail the firing order (1-5-3-6-2-4 Isuzu standard) and the cross-flow head design. Look for diagrams showing the valve spring free height and stem-to-guide clearance. A clone manual often gets the 6-cylinder order wrong; the OEM PDF does not. isuzu 4hf1 workshop manual 6 cylinder pdf
Specialized guides for the in-line injection pump and fuel filtration are available on Scribd . If you specifically require a 6-cylinder manual, these