The body is the same bottom outline from the standard to the squared. Only the window frames, the top rear line, and the side scoops changed, really. The lexan is pulled from the same mold, I know that.
The lines of the chassis where the front of the rear arms mount changed to help prevent rubbing of the new 'straight' arms on the chassis. The original X - 6 rear arms had a small molding bump on the front along the hinge pin to help move them back and clear the chassis, which was straight. Through running the 6 pretty much the whole team liked running arms and hubs forward, so I made it so the Squared arms could move even a touch more along the hinge pin.
The outer rear corner (where the lower rear body rubs ever so slightly) is a touch further back... that change doesn't have any specific reason, just the way I ended up drawing the chassis.
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