Harmonic balancer oil leak in magnum.

I have had bunch of Magnum 5.2 and 5.9 engines apart over the years, some for repairs and some for upgrades and rebuilds. Never had one leak from the front seal yet, and always set the cover in place loosely, install the balancer completely, snug all front bolts starting near the bottom, tighten all front bolts, then install oil pan. Only did a couple where the oil pan was left in place and tightened the oil pan bolts to the timing cover last. If you have even had a factory Magnum balancer leak when re-installed with the same bolt, washer, and thin plastic washer that TrailBeast mentioned, it must be a technique issue or a problem with seal not being installed correctly in the cover, or getting distorted when hammered into the cover. How exactly are you removing the oil seal and installing the new one?