Something I’ve seen mocked up by AggeIw (https://aggeiw.deviantart.com/art/Give-me-a-Hand-216238791)
It also begs to reason why Vader would even scream over his mechanical arm getting severed. Maybe there were nerves connected during Vader’s suit construction or something?
3PO feels pain when he’s banged around, burned, ect. And the droids in the stupid torture scene are all screaming in pain. If they feel is somehow, I’m sure Vader does too.