DeviantArt has been very fernickety about nipples recently so uploaded the uncensored version here:

Ever since Lord Vader landed on Tatooine in search of the stolen plans, he'd personally choked a dozen of his senior officers. There was a growing sense among the ranks that something about the planet made the man even more erratic than usual. Still, I was unprepared for just how far his mind had slipped when he summoned me down to the surface.

He expounded upon his plan from atop a dune overlooking Mos Eisley. It was, simply, absurd.

When he finally lowered his gauntlet and my airway opened up again, I gasped in a lungful of dry desert air. "My mistake, my Lord. I misspoke," I wheezed. "How foolish of me. Your plan is perfect in every way."

"The disguise will be impenetrable," Vader boomed. "The locals will never suspect a thing. I will walk amongst them, completely unseen. Those data tapes will soon be ours. See to it that my orders are carried out precisely."

Who was I, a mere insect, to question the Emperor's right Hand? I contacted the armorer on the Executor to begin fabricating the components at once. They found a record of the requested anatomy within the databanks.

"But… equus aren't even native to Tatooine," muttered the armorer.

"Get it done or I'll kill you myself," I snapped.

It was one of the highest honors of my Imperial career to be entrusted with disassembling a man of such rank. I levered off his armored chest plate, lifting the bulbous rubber breasts into place. He examined them contemptuously, his rasping breath the only sound for a long, dreadful moment, ready to kill at the slightest deviation from his specifications.

"They are inadequate," he growled, crushing the windpipes of two engineers. "Bigger."

Next came the codpiece, requiring considerable twisting and yanking to detach. His mechanical manhood fell away into the sand. As he came apart, I was startled to realize just how small the seething, shrivelled nugget of Sith Lord encased in there really was. We detached the Dark Lord's arms and legs, laid him on the dunes and welded his new limbs into place.

Normally any adjustment to his armor would be performed in the safe and sterile environment of his meditation chamber. The sand was coarse and rough, and of course, it got everywhere. I never dreamed, when I signed on to the Imperial Navy, that I would one day be vacuuming dust from the Dark Lord's rubbery, horse orifices.

One of the assisting technicians was sweating even more than the desert sun deserved. She saluted with a trembling hand and leaned close with a terrified whisper. "It's his radiator."

"What?"

"His internal radiator. It's malfunctioning. It can't keep up with this planet's heat. His blood is literally boiling. I think... I think he's been delirious since the moment he set foot on the planet. He has no idea what he's saying!"

With sinking dread, we turned to look at the Dark Lord we'd rebuilt into an equus mare, frolicking on the dunes.

"One of you will need to ride me to the settlement," boomed the obsidian and durasteel mare from the speaker embedded between its interrogation droid-sized breasts. "It would only look suspicious otherwise."

"What happens to us when he recovers his senses?" she whispered.