Don't search through your toolbox for the most convenient tool to turn the diesel engine over when servicing the valves. Get this engine barring tool which is made specifically for the job.
Half the price of the Cummins branded tool (5299073)
Steel not plastic
Made in the USA unlike the Cummins tool
Uses 1/2 drive ratchet
Functions the same as the Cummins tool
Insert the diesel engine barring tool into the flywheel housing to engage the flywheel ring gear. The engine can then be turned by hand using a 1/2-inch drive ratchet or breaker bar.
Designed for 5.9L and 6.7L Cummins B and C Series engines.
Take a look at this quick video below, where Brandon discusses the Geno's Garage engine barring tool and the Cummins engine barring tool: