So I was thinking about Mega Gargants after having built my Warstomper, and remembered in the Gitz tome it mentions that Dankholds can grow to fit the space they're sleeping in, and that the tallest are nigh as tall as Gargants, and that makes me wonder if that also refers to Mega-Gargants, given both excerpts. So, I threw together some rules for what I'd expect the biggest, dumbest Dankhold to be. I might even draw it as a design. I picture it as a bloated, slobbering toad of a Troggoth who's so fat its legs barely work and it drags itself with its arms.
I'd expect it to be in the 550-600 point range.