I've purchased an e-bay top/bottom & gear shell. All good.
I had to retain the battery frame in the bottom shell, it has an adhesive but is easily removed. You'll use it again.
I'm gonna say, if you like working on things & have a little "wrenching" finesse, the change over is simple. Look at several video's first, go slowly following what you've learned. Take picture's, & mark on tape the screw sizes next to the motors etc.
A quality screw driver set available on "Phantomhelp.com" will be necessary to complete the job.
I'll look back & check on the seller of shell I purchased.. It's been a while though. "Boxer" is an Excellent tool kit.
labeling an egg carton mounted securely to your work surface makes a perfect place to remove & place screws when disassembling.