Originally Posted by Frank Reiner

hb:

Although the locating dowel in the crankshaft, and the corresponding holes in the driven (flex) plates must be matched for the plates to be bolted to the crankshaft, the driven plates can be installed if reversed front-to-back. If that occurred, the ignition timing will be in error. There are timing check holes (alignment holes) in both the plates and in the flange of the starter ring gear carrier. The crankshaft dowel, the check holes in the plates, and the check hole in the flange must lie on on a common line.