Hello Max, First off all you will need a .v3o file which will be replaced for the original model. First Step: Start the editor, then load a mod and click on Yes. Second step: Hit F1 and search under Vehicles LA Fire Department, and look for the vehicle you want to replace. Third Step: Click on Editor next to the selected vehicle and there will pop up a little screen. Almost at the bottom you will see a browse button, which will allow you to search trough maps for .v3o files. Step 4: Search for the model file name of your new truck/car. It maybe will be called mytruck.v3o (<-- This is an example on how a model file will be called. Step 5: If you have found the right model file name click on it and click on Ok, and do the same for all the other. Now select in the F1 Menu (Prototypes) your vehicle and place it onto the map or in the fire station. (Load the Freeplay map. Also don't delete the old vehicle yet!) Step 6: The vehicle you want to replace is still in the fire station, select it and click on your bottom left of your screen Properties. The vehicle will have a name, write it down or remember how its called. Step 7: Close the properties screen, and select your replaced vehicle and click on properties. You will see a small bar with name and type there the original name of the old vehicle. Step 8: Delete the old vehicle, and put your vehicle on the place where the other should be. Save the map under Freeplay and close the editor. Now its time to test it ingame and look if it works! Goodluck!, RedHawk504.