Back when I worked at the truck transmission place, we had a huge Cat axle from some kind of haul truck.
24 inch ring gear!
The pinion looked about as big as a 5-gal can, and had to be hoisted into place. The housing looked to be bracketed for a 3-link suspension setup. Multi-disc wet brakes inboard of the planetary hubs. The whole assembly shipped out at almost 6000 lbs...