Just trying to find out how to change vehicle type at any gate or parking spot. Read the manual did see how to change from air stairs to cargo lift or any other service vehicle on my freighter
If you want to change it on a single (or many) gates, there's an option in the GSX Parking configuration editor to do that. If, instead, you want to change it globally, you must edit the relevant field for front and back loaders in the GSX Airplane configuration editor.
When the parameter is set to "Auto", what decides the selection is the "condition" parameter in the [Couatl] section of the vehicle SIM.CFG file. Usually is the door's height, for example, the Cargo Loader can be used only if the door height is between 1.92 to 3.40 meters from ground, and the Higher loader will be used from 3.40 meters onward. The Belt Loader will go from 0.9 meters or more.
This means, if the parameter is set to "Auto", if your airplane cargo door is located at 1.5 meters, the Belt loader will be used, if it's located at 2.2 meters, the selection will be random between the Belt loader and the standard Cargo Loader.
If, instead, you set a specific vehicle in the Airplane configuration, that one will drive the selection provided, of course, the "condition" parameter is respected. This means, if you have a door located at 1.5 meters ( too low for the Cargo loader to reach ), and specify Cargo loader in the airplane or parking config, no loader will appear.
How do I change my PAX door on the top forward to a large upper cargo door? GSX sees it as passenger entry not a cargo door. Please help.........
You can't change a passenger door into a cargo door. If you want to create a config for a cargo airplane that is not supported by GSX, you must MOVE one of the two existing cargo doors on the right side, to the new position on the left side, AND rotate it 180 degrees, so you'll have the direction arrow pointing OUTSIDE the airplane. You can only have a total of two cargo doors.