EDIT: Sorry, just found out it's an RB5 (didn't look well at the front shock tower). Old post:
Check this out:
On this car I think the cab doesn't look as big as on the show model:
In fact to me it looks like the RB6 I snapped has a different body altogether?
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Perhaps you could still try out an RB5 or RB5 cab forward shell? And, how about making the windows smaller on the car? It might visually reduce the side of the cab. Also, on other pictures than the release pictures (side views) I noticed how big the cab indeed is! I will tune down my opinion about the RB6 shell a bit now - I still really like how there's not too much going on in it's shapes though!