[sparkycuda]

Yes, ribs for strengthening but also anti-abrasion. These machines were used to push in all kinds of material. WV and KY machines worked slot-dozing in a lot of sandstone, so experienced extreme wear on the ends - I've seen those ribs completely worn away. Often users would add more abrasion resistant steel on the blade ends before ever putting them to work.
While the weight is extreme compared to other RC dozers, it was huge in real life - largest production dozer in the world. Big dozers are just heavy!

You are doing a great job!

Ken