I picked this engine up from a friend of mine, it was locked solid and full of water. Australian made by Pecision Engineering in Sydney. It is of course a Briggs and Stratton clone engine, Amplion also manufactured a clone as well. I have recently acquired an Amplion and there are some minor differences in the build.
CyberJack supplied some material showing the genset which I believe mine was once a part of. I found army green paint on mine so maybe it's an ex army unit.