[Lbert]

It was the harmonic balancer after all!

Although the crankshaft pulley did not wobble and the thin rubber on the harmonic balancer looked intact, the weighted balancer portion (outer section) of the harmonic balancer is out of place against the inner ring or section. Both sections were free floating against each other. As a consequence the engine vibrated severely.

To test the harmonic balancer, clamp the inner section of the harmonic balancer on a vise to hold this section of the harmonic balancer down. Grab the weighted outer ring with both hands and turn it. If you are able to turn the 2 sections against each other, then you have a bad harmonic balancer.

Thank you to all that have responded!