1st thing I wondered when dling this was the file size. After dling the file I looked in the pbo and noticed you had the m2a2 textures in there. There is no purpose for them being in there, so you should delete the m2a2 textures in the .pbo to make the .pbo smaller.
I went ingame with it and it was pretty funny and reminded me of one of my first addons made (a m113 with t72 turret).
Anyway its looking good so far maybe just add some rounder wheels and tread.
But one of the most important things you did wrong was the LODs. You have 5 LODs that are all the same, that will make you lag when you have alot on screen. But ya this is a beta so...
Keep working on it