There was also an old two bladed Navajo around that time as well. Never seen a two blader before. Must have been a late 60's model, old piper paint scheme. Don't recall the rego of that one.
PDN was a two blader when I first saw it. Couldn't figure out what sounded different about it in the circuit compared to other Navajos until it taxied in & shut down.
DF.