How to Find Your DLC Number in Fallout: New Vegas
In Fallout: New Vegas, codes for items from DLCs are represented as xx in item codes, and they start with a unique identifier known as a DLC code.
A DLC code is a two-digit number that indicates to the game which DLC an item originates from.
This code varies for each player because it's determined by both the number and type of DLCs they have installed.
Why do some item codes begin with xx?
Item codes that begin with xx pertain to items from DLCs. The xx acts as a placeholder for the DLC code, which is unique for each player.
This uniqueness arises from the load order of the DLCs, which affects these numbers. The only 'fixed' IDs are those from the 'base' Fallout: New Vegas game, which always start with 00 because it is always the first to load.
Console method
In the game, Fallout: New Vegas, you can open the console and click on an object native to the world. The first two numbers of that item's code will represent the DLC code.
Brute force method
If the above method proves ineffective, consider inputting the following numbers in place of the xx field:
010203040506070809... and so on.
One of these numbers should be the correct DLC code.