Discus, Heavylift Cargo is an operation with a few crews working out of Australia, running one old B727 freighter under some other offshore AOC name. They did have the world's only airworthy Belfast freighter as well, but I think it is now grounded. I could be wrong on the airworthiness part, but Heavylift Cargo no longer comes up on the CASA website as holding an AOC.
The Hevilift under general discussion here is a much larger PNG company.