At last, I could publish my complete Tank TF. It's the same transformation, but I've only changed some parts of the arms, the back, the torso and the legs. Thanks for Eric Landreneau for the recomendation of making a bigger turret/cannon.
Main pose with weapon! =P
Same pose, but lowered gun.
Watch out! He's aiming at you! =D
AS you can see, it reminds me alot of Bumblebee (from the TF Move, you know...and the shoulder design...). Also I've managed to changed a lot of the cannon, making it more "Bulky" and more long.
Actually, when it transforms to tank mode, it reminds me a lot of that tank in the Halo game series...Quite a coincidence xD