ONLY APPLY SP3 FOR TRS2004 TO TRAINZ RAILROAD SIMULATOR 2004. DO NOT APPLY THIS SERVICE PACK TO ULTIMATE TRAINZ COLLECTION OR TRAINZ.
You need to verify that you are downloading the correct patch for your build. To do this, launch Trainz and look for your Trainz Build Number located at the bottom right hand side of the splash screen and note down the Build Number for later.
Select the Quit button and return to the desktop.
Download Service Pack 3 for Trainz Railroad Simulator 2004 to your desktop, or to some other convenient location.
Locate where you downloaded the service pack to and double click on it to launch the installation from your hard drive.