Open OpenIV and enable edit mode

Open the game directory\MODS\X64E\levels\gta5\vehicles.rpf
Replace the FRETITCONT2 in the 25K folder to replace the GTA5 original mode

Open the game directory\MODS\CommON.rpf\data\levels\gta5
Replace the files in the Data folder TRINS.XML (optional, because this is the group file)

If it is 2372 or more, you need to replace a trains.xml file:
From MODS\UPDATE\UPDATE.RPF\Common\Data\Levels\GTA5
2372 or more version of the two trains.xml need to be replaced, otherwise only two flat panel freight trains

The model is from Train Simulator, All copyrights belong to official Chinese players