There are 5 variants for torso, arms and legs armor pieces. While the helmet has only 2 armor add-on upgrades (Medium & Heavy)

• Armor Add-on "Ancile". This armor add-on is geared towards conventional combat with ballistic weaponry.
• Armor Add-on "Vigar". This armor add-on is designed to fight more advanced adversaries with energy weapons.
• Armor Add-on "Svalinn". This armor add-on used mostly for area with radio active materials.
• Armor Add-on "Evalach". Further development of Ancile and Vigar models, with combined power to withstand ballistic and energy assaults.
• Armor Add-on "Akshaya". A special Armor add-on with better build and shocks, intended to move a large number of objects.
  

There are some uniques

• Unique Torso "Aegis". A further developed Evalach model, provides protection to the upper torso and reflects damage back to attacker.
• Unique Arms "Tarnkappe". Akhsaya model with attached Stealth Boy, for clandestine operations.
• Unique Torso "Diver". An early developed torso armor add-on, intended for under water operations.
• Unique set "Conductor". A unique set of Synth PA that was acquired and modified by the Railroad. The set material increases the chance of the user to hide in shadows.
• Unique Torso "Hermes". A special torso model that has advanced circuitry and mechanical design to increase the speed and jump height of the user, regardless of the type of Power Armor legs.
  

The legendary chest piece Pale Rider's Aegis





The unique chest piece Synth Diver and Legendary Tarnkappe's Arms



The unique set Conductor



The unique chest piece Hermes

Inside Lexington Pharmacy, an unmarked location in Lexington, there is a rogue synth who somehow has this understanding of crafting complex Synth Power Armor mods. You can buy various mods from him, be warned, his price is exorbitant. A special workbench is located in the pharmacy, use it to craft the basic version of Synth Power Armor.

Other location to get the Power Armor is in Institute FEV Lab, you will find it during certain main Fallout 4 questline.

The Conductor Synth Power Armor is located in Railroad HQ. While modifying the set, Tinker Tom managed to get another set of Arms, he buffed the metal plating increasing the armor rating.

There is a pair of Hermes armors. One is stolen by Chase, a former Courser, while she was escaping from the Institute. The Power Armor was almost destroyed, but luckily the advanced machinery in the torso armor survived. It is now abandoned somewhere outside of Acadia. The other Hermes armor is located somewhere inside Sandy Coves Convalescent Home. It is unknown how the armor piece managed to move to the nursing facility.

Fallout 4 Engine limitations, bugs & potential conflicts
 

• During crafting with Power Armor Workbench, if you select an armor add-on, then select another, the previous armor add-on does not disappear. This will make a mix armor add-ons. Just make sure you know which armor add-on you want to create and apply that to the armor piece. Disregard the mixed display, the armor add-on will be corrected when you enter the Power Armor frame.
   
• Sometime after crafting an attached item, such as Jet Pack, it is possible the item was attached sideways or floating. If this happened, save your game, exit game, re-enter the game and reload. The item will be attached properly.
   
• Headlamps and Torso-lamps sometime do not work properly or attached in different part of the body. As the issue with attached items, this issue can be fixed by save the game, exit the game, re-enter and reload. However, if these lamps issue persists, then you have node ID conflict with other mod. This mod was tested to work with lots of other Power Armor mods, but we never know, some mods might conflict.
   
• The Diver and Conductor armors uses torso slot, therefore it is possible to wear a Power Armor helmet inside it. This will clip the armor. You're not supposed to wear a helmet inside the armor, other than Synth Diver Pilot Helmet.
  

 

• As this mod uses vanilla interior cells, it is possible there is a conflict with other mod that uses the cells. This mod modifies Lexington Pharmacy, Institute FEV Lab, Railroad HQ & Sandy Coves Convalescent Home.
   
• This mod is developed without AWKCR, so... don't use it.