I would like to see something like #24 where the dozer is pushing dirt into the I and possibly the missing portion of the I is outlined?
I think it's a clever idea, but it's a little hard to read in #23 & #25. It needs to be easy to read. When it's just the G that's missing it has symmetry problems/looks incomplete.
Another idea for a variation on #24 - why not make the top half of the letters a different color like they had just been filled in/graded out? Rather than in-progress, just completed?
It might be a terrible idea, but I'm trying to help you out.
I would like to see #49 without the piece of the letter G missing and the dozer offset to the left. Sorry, hard for me to visualize how these are going to turn out without seeing the final product.
I still think #49 is your best concept, but it's just not quite right. I would like to see the G filled in, but still a color representation of the dozer filling in the letters - like a map of the layers of the earth. I would also like the bulldozer to look less like a cookie cutter, if that makes sense.