MIRRORING THE REAR!!!
I started with the top Rear Section and cut off half of the Section behind the rear wheel wells. I also cut the Donor Rear Section in the same way. Next I cut out the lower part of the body sides, so that the Donor Body Section fits in place as shown.
Another View...
The I cut the plastic around the Engine Compartment, so that it is flush with the New Bottom of the AeroTrec!