Hi. If I did my initial MECIR on a Baron in OZ and want to do the renewal here in a BE-76 do I need to do a TR/Endorsement on that before I could? I presume yes I would have to???

You assume correctly.

This is on a JAR CPL?
Here being where? OZ, NZ? UK?

In the UK
No definitely not, you only need an MEP and an ME-IR.
There's no type rating for the duchess. :)