You can't see the difference, but your engine can.
Some manufacturers claim their engine parts meet or exceed John Deere specifications. However, these look-alikes cannot compete with the continuous technology improvements of genuine John Deere parts. Even though the differences might be small, the advancements make a big difference in retaining the performance and reliability of John Deere engines.
John Deere crankshaft dampers protect your engine from harmful vibration that could occur when torque is applied. Dampers not only protect the crankshaft, they help extend belt life and reduce gear wear. Your damper should be replaced whenever an engine is overhauled or replaced with a remanufactured engine.
John Deere recommends changing the crankshaft damper at 4,000 to 5,000 hours or five years, whichever comes first in the application.