EDIT: Slight change, due to me being a total moron. The file is now packaged properly as of V1.1, and not in an "optional" folder. "Cause I'm an idiot.

This is a very simple mod that Changes Irileth, the housecarl of Whiterun.

The changes made are as follows:
Armor is changed to the Whiterun guard outfit. Anything that changes the outfit of the guards of Whiterun will change Irileth's outfit.
Changed her hair (Thank you Apachii, you generous, creative soul, you). The vanilla hair she had is ugly and the other mods that alter her tend to give her, long, luxurious, "glam" hair. Frankly I thought that was inappropriate.
I slightly altered her warpaint.
She walks like a woman now, not like some weight lifter with a rod up his butt.
Her weapons may have been changed. I think. don't remember exactly, you'll find out when you fight the first dragon I suppose.

I have not altered her skin or face textures or her body. She should simply take on whatever NPC body and textures you have installed, if any.



Requirements:

ApachiiHair
ApachiiHairFemales
Dragonborn DLC

Obviously my game is modded. Mods I recommend that are active in altering the vanilla aspects of this mod are:
ApachiiHair Natural Retexture
Superior Lore-Friendly Hair
SG Female Textures Renewal (including the optional Elven Race Patch) 
Cloaks of Skyrim
Armor and Clothes for Females (not on Nexus).
I also use many texture changes. Your Irileth may not look exactly like mine, but I don't think she looks so different from Vanilla.