Could be anything or any brand manifold Top gun , need a pic of manifolds.
The most common Delorto distributers in OZ were / are ? Lynx industries. The produced their own manifold and rubbers and air cleaners.
I installed a few sets and they were OK. I liked watching the rubber manifolds pulse at idle they were so thin.
I don't know if Lynx are still in the game , they were Sydney based. Google them top gun and see what happens,