The 60’s in Aus. was a time of re-powers.
Petrol and under powered diesel trucks were re-engined and apart from 3 or 471 GM’s, many smaller operators fitted Leyland 400 or sometimes a 5-cylinder Gardner.
Commers scored the 6V53 GM and soon this engine was optioned in International, Dodge and even Bedford which still offered it’s own engine as well as the Leyland 400.
Never ever saw an AEC engine in a re-power though, the 470 did not have a good rep. down under.
It took a long time for the 505 to gain acceptance, even with Leyland practically giving AEC trucks away.
I payed $10804 for my Monarch in 71, 2-stroke Commer was around $13K.