www.madmaxmovies.com

I was lucky enough to see MAD MAX opening day in 1979 in Portland, Oregon. I was the projectionist at the Broadway Theater. Watching this movie several times I could tell the film was dubbed even though the actors were obviously speaking english. Produced with assistance of the Australian Film Commission! Ah! It's Australian! To this day I believe the actor that voiced Mel Gibson was an actor (and voice over artist) who worked often at the time. His name is Roger Davis.
https://www.imdb.com/name/nm0205380/?ref_=nv_sr_srsg_0
Google him and listen to his voice. It's him. I could swear it is.