This mod adds in a variety of different types of guard and replaces the original guards. List:

• Imperial Militia
• Imperial Constable
• Imperial Marines
• Imperial Guardsman
• Imperial Yeomanry
• Imperial Cavalry
• Imperial Scout
• Imperial Messenger
• Cheydinhal Yeomanry
• Bruma Yeomanry
• Anvil Yeomanry
• Bruma Militia
• Chorrol Militia
• Chorrol Yeomanry
• Kvatch Yeomanry
• Imperial Magician

And many more that I cannot recall.
*IMPORTANT*
Make sure you have "Militia with gun" and "Militia with gun pt2" enabled on your launcher.
Also Despite the name of the files the militia don't have guns but hopefully soon they will have flintlock pistols.
If for some reason the guards don't have hats then download pale_riders hat mod.