This isn't exactly a mod, it's more of a modder's resource. What this 'mod' does is restores line 328 in Appearance.2da to have the correct model and texture values. In other words, it adds an unused alien to the game, a Chadra-Fan. You can implement it in a mod by using the restored appearance slot on an NPC, or just put the included disguise on the NPC. Don't expect a full range of animations, it uses the exact same animations as a Jawa. Use the Attached Files link under the picture to download.
Here is a picture of the little critter: