Does anyone know the specific for ID prefixes "xx" for the GOTY edition on steam?

Specifically the chinese stealth armor. But also any item that has a form ID beginning with xx on the wiki form id page.

The xx prefix refers to the load order of the dlcs/mods as it appears in FOMM or Wrye Flash. If you have your dlcs ordered correctly it should be:

Anchorage- 01
The Pitt- 02
Broken Steel- 03
Point Lookout- 04
Zeta- 05

So the base id for the Chinese Stealth Armor should be 0100c18f.