Steve,
Your Nashorn is a clean, well executed build. I very much like the added details, especially the seat frames!
I wasn't impressed with the look of the MACO tracks when I saw earlier images of them, but they look much better in yours.
[Edit] This also reminds me of Alex Clark's Nashorn in his books. Yours is pretty darned close to the level of his.
Please post some more "before paint" pics.