It is a bit of a hog on fuel....
There is no original tank on this anymore, didn't have one when I got it. Someone built a tank that is mounted in the deck, holds around 300L or 79 US gallons
I would kinda like to find a 5.9 and put it in, I'm sure it would get much better mileage.
I can't say what the gearing is, in low it sure does crawl.