Doc Customization 3
The Doc Customization 3 is a Belsavis Companion Customization Vendor (Republic) item which can be found in Star Wars: The Old Republic.
To get this companion customization, simply go to the planetary Companion Customization Vendor and purchase it.
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How to get the Doc Customization 3
The Doc Customization 3 is a customization you can purchase directly from a vendor in-game, you don't need to purchase it from another player and there's no secret way to get it. All you need to do is go to the vendor and buy it, and most companion customizations only cost between ten thousand and twenty thousand credits.
The Belsavis Companion Customization Vendor on Republic side is located up on a platform with other vendors near where you load in. The vendor is a golden droid named M-5Q5 standing in front of a market stall. The quickest way to get there is to use the Belsavis heroics quick travel (otherwise just fly there on your ship). You'll likely be able to find this customization at the Republic Ilum planet customization vendor as well.
Imperial Side
This customization can also be purchased on the Imperial side from a vendor called Denvas Ran, Companion Customization Importer located in the Cartel Bazaar section of the fleet (southern elevator, there's a quicktravel point there). The vendor is inside a shipping crate.
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