looks good, whats the trianglecount?
did you make sure it can go up and down ?
and why are the protection bars above the head removed ? (the part where they are most needed, you left them out )
well, looking at the ref. and the model, if you look on your model, the bars above the head are to far backwards. On the ref they are above the drivers head (the way it should be) your model is a very close match, needs some tweaking and proportion fixes i think