I'm assuming you have a spoiler on the 40th?
If so, it has 11 mounting points. 4 bolts, and 7 plastic pop rivets. That's a lotta holes to plug... (
that's what he said...)
If you swap your rear hatch, you'll need to undo the support braces, undo the mounting bolts, and cut the rear hatch wiring harness for the defogger and 3rd brake light. Most people get plugs installed to make it easier, but that didn't suit me so I had my hatch completely re-done for my wing.
The other concern with having a different hatch on your car, is if you buy one from someone else, the VIN number on the hatch won't match the VIN of your car. So in the unlikely event of an accident, your insurance is not liable to replace the other hatch if it gets damaged in anyway.
Just something to consider...