M3 Stuart-esc
Barrel is too long and the M3 could not go 51+ mph.
Also, it isnt the M8 because that could carry 80+ rounds of ammo and the .50 cal was not mounted on the left.
EDIT: I just looked at some blueprints of the M18, it did have the bars just like they are modeled here across the front and over the center from front to back, the .50 cal was on the left and set back. Even that little lid that is bolted or riveted down on the left front top of the turret is accurate. I'm quite confident it is the M18.
EDIT #2: I did not realize that the M18 only has a 3 speed transmission. I hope people realize that if they think the T34 has a hard time climbing hills just wait until they attempt it with the M18, it will have even LESS available power. Also, just a reminder that the M18 has little more practical armor than the M8 Greyhound, so it will be a camper or a flanker, but not a 1v1 level playing field engagement tank.