they are some good shots. a suggestion would be to get a bit of dirt to "hide" the bottom run of the track in the first pic so there isn't a gap. easy enough to touch up in photoshop. if you notice on most of my finished pics my bases are rutted since they are generic and the rut hides the track not sitting 100% on the ground.
the second and third pics are great. i like the way the 3rd pic empahsises the barrel length and they look good with the blue sky. the 2nd pic with the sunlight and the shadows could easily pass for a shot of a real vehicle. your weathering continues to grow on me every time i look at it
sometimes i will take a ground eye view of a ww2 vehicle, make it gray scale, blur it a tad and add some grain and see if folks think it's real.