To give you the most accurate guide, could you tell me or what game/software you were looking for when you came across it? This will help me confirm if it's the SpaceX mod or something else entirely.

Locate your KSP directory (usually SteamLibrary\steamapps\common\Kerbal Space Program ). Open the GameData folder.

Full-scale models with realistic engine clusters and stage separation.

Always download from the official KSP Forum thread or Spacedock .

While the SpaceX mod is the most likely candidate, "KK" can occasionally refer to other niche projects:

Includes functional grid fins, landing legs, and "droneships" (ASDS) for autonomous sea landings. 🛠️ Technical Details & Installation

Rarely, custom user-made installers for codec packs use short abbreviations.

Early and updated iterations of SpaceX’s next-generation Mars vehicle.