Yes, true but not entirely correct. VH-MXK was used on the Ok-Tedi contract VH-KZL (not sure if that was the National safety council's rego for the aircraft, but it was purchased from them), and VH-NSR. It was late 80s and early 90s.
Both bought for a song from the remnants of the National Safety council's ashes by Guy Lloyd- an astute character.
Used then for charter in the PNG region when there was a lot of oil and gas exploration going on. They found a lot, hence Oil Search and Exxon's presence in the region now. They proved very handy after the dispute, flew lots. NSR was a -42 and a good machine.
The Merlin was based in Adelaide and was another aircraft bought cheaply-from the old DCA, I think?? but not as successful or useful. Mostly charter, but I was not living in Adelaide then so not sure.
I think the King airs ended up in Darwin on air med operations for SkyWest.