That's a good-looking machine you have there.
I've always liked that particular model, and have built one or two in my day...
If you don't mind, I would like to make a couple comments, particularly if you are going to do more of these for your diorama. I can't see any detail in your pictures,so I'm operating from past experience and a few assumptions. If this is totally off-base, I apologize in advance.
1. If this is a Tamiya or Tamiya knock-off kit
, there may be motorization holes in the lower hull. Those need to be filled and hidden. Sheet styrene and putty should do the trick. Since your vehicles will probably be weathered for your diorama, it's important to paint AND weather the bottom of the tank as well as the top, and the inside surfaces of the road wheels, too.
2. Likewise, the drive sprocket attachment points. The older molds had cut-outs in the upper hull where track tension adjustments could be made. Those cut-outs need to be filled, sanded, etc. I used a combination of sheet styrene and putty. I can't remember this model completely, but if an axle is used for the front idler wheel, make sure it can't be seen.
3. The underside of the fenders seemed to have an awful lot of ejection pin marks. Take some .010" styrene, cut it to the length and width of the fenders, and glue in place. Problem solved.
4. Check the INSIDE of your muzzle brake. There's probably a mold seam there. It can be removed with sandpaper-on-a-stick. If you can't completely remove it, hide it with black pastel chalk dusted judiciously inside. A well-placed drop of white glue works really well, too.
5. The mantlet cover was made (I think) of canvas, and should be a different color than the rest of your machine. When I worked with the USMC in Cuba in the eary-mid '70's, the tanks were a faded olive drab, and the mantlet was a faded olive-sorta-brown color, lighter than the O.D. on the steel. I think the cloth simply weathered differently than the steel. That kind of detail can really make your model "come alive".
6. If you are going to pose figures on your cupolas, make sure that no one can see down into (or through[:0]) the tank unless you have built some form of interior. Nothing can make a realistic model look more like a toy any quicker. Take some .010" styrene and cover the hatch area where the cupola meets the turret. You can even put it just below the figure's feet to hide any lack of interior. Make sure you paint it flat black. One good rule of thumb: If you want to have an open hatch, stick a figure in it. If no figure, keep the hatches closed (unless, of course, an interior is present.).
There's probably a few other things, but they can wait, 'cause I can't remember
Anyway, hope your diorama turns out great. Keep posting pictures as the project develops!
Gip Winecoff