Not sure how much it may still be of use ( probably don't care much for 3D printing the entire upper Chassis again ) but the upper Chassis laid down flat horizontally and 3D printed like that is a kind of "unfortunate" layer orientation.
Unless you don't care about Layer Lines or aren't bothered with the huge amounts of spackling and sanding, you'll have to do to get rid of them you'd have better faired with placing them on the split line and printing the parts standing vertically upright - Possibly even benefitting from not having to use any time-consuming Support Material for the roof section.