I am fully aware of that, read my post againThe car had a different rear end in 1998...
I've been an admin at SMCars (blueprints and stuff) for years and all too often we had people complaining about some lines not matching up. They are guidelines and should always be used in combination with - preferably - hundreds of reference photos.
With these blueprints you can model 90% of the car somewhat accurate. You do the rest by looking at the actual car instead of some black lines.
And yes, I do have experience with 3D modelling of cars. I've done tons back in the days and quite a few without any blueprint whatsoever. Pick your best side view photo and just start recreating the shapes. Again using actual photos to guide you through it. A missing rear end is almost as good as the full thing.