Ensuring proper alignment between the crankshaft and the bell housing is crucial to prevent premature wear on clutch discs, pilot bushing, transmission bearings, and transmission jumping out of gear. The bell housing alignment tool is precisely designed for this purpose. It's effortless to use; all you need to do is mount the precision ground arbor to the crankshaft and mount the bell housing to the block. Then, slide the aluminum alignment hub over the arbor and through the bell housing transmission alignment hole. If the hub goes through smoothly, it indicates proper alignment. However, if it binds up, there is a misalignment problem that requires fixing. It's also highly recommended that you check the transmission mounting face of the bell housing for true indication with the crankshaft. The package includes an arbor, hub, drill bit, alignment pin, alignment pin drill bit, and arbor mounting bolts. Please note that this product contains a chemical known to the State of California to cause cancer and birth defects or other reproductive harm.