Just to answer the OP's post about the suspension on the Japanese FG538s. It is the same as the Aussie trucks, as I've sent springs bushes, shackles etc up from Australia to PNG for trucks I run there. The axles are narrower than the Aussie versions, but apart from that there's not a lot of difference in the running gear. I'm not absolutely sure but I think the white dual cab truck in the picture above is one I bought for PNG a while ago, if not, it's its twin, the box across the tray is a winch and the one in the corner is the winch controls. The Japanese versions run a 4.6L diesel, normally aspirated.
Trev