Internal/External balanced motor

A few year back I had a my 318 rebuild and did not know much about rebuilds...The only thing updated in the complete rebuild was the 360 heads milled and a 340 cam installed. (never asked for balance/blueprint etc.)

Is there a way just by looking at the vibration damper to know if the engine is balance internal or external? How about stock balanceing. As stated yesterday, my damper looks a little worn...the thin rubber seal has become very brittle and drops off when rubbed, however I don't think the damper has shifted out of phase.

Thanks