Hello Ron,
There are only two dowell pins on the front of the crankshaft. There is an additional large one on the rear of the crankshaft to index the flywheel. The rear dowell is about a 10mm diameter while the fronts are smaller, possibly 6mm diameter. Caution even though the front dowel slots look like they are positioned 180 degrees apart, they are not. You can force everything together 180 degrees wrong. Be certain to index the vibration dampner correctly or the dowel slots will not line up exactly. The M127 engines tended to have some issues with the connection of the vibration dampner and crankshaft coming loose and damaging the end of the crankshaft. The BBB describes an upgrade to replacing the original bolt with the new stretch bolt and spring washers to prevent problems. Engines with the added strain of AC are even more prone to this problem.
In any case make sure your vibration dampner, crankshaft , and dowell pins fit nice and tight. You can use a little Loctite stud and bearing mount if any of these clearances are marginal.
Replacing the front crankshaft chain sprocket is aways recomended when the engine is down. These are fairly inexpensive and are the most critical sprocket. Check the key and slot for play under this sprocket also. The points of the teeth on an old sprocket wear to a sharp point. The teeth on a new sprocket have nice squared off ends. A worn drive sprocket increases chain wear and will eventually cause the engine to be more prone to chain failure.
