Okay, there are several things that I see but not all relate to your missing vehicle. There are some mention of issues related to vsync being turned off in the Nvidia Control Panel causing the inability to enable vsync in the game. This has occasionally resulted in loss of use of a keyboard or mouse. If that ever happens to you, the fix is enabling vsync in that control panel.
There is an EOS error saying that you don't have permission to advertise presence. This is usually due to antivirus software so if you create an exception in your antivirus for the game folder and saves folder that should disappear. Again, not related to your vehicle and seemingly not causing you any problems, just noting it's there in case you do run into problems with the game.
Lastly, the game is telling me that your jeep is located at -1052.2, 81, 1714.5. The first number refers to east/west where negative is west, second number is elevation, third number is north/south where positive is north. Go to where you think the vehicle should be, open your map and put your cursor at the point of your icon on the map. At the top is your east/west and north/south location and near the bottom left of the map it tells you your elevation. See if that matches the above location. If your elevation is, for example 20 then your vehicle at 81 is 31 blocks in the air and god mode should allow you to go to it and pick it up. If your elevation is say 100 then your vehicle is 19 blocks underground. See if this helps finding your vehicle.
I am not familiar with the Undead mod so I do not know if it can effect vehicle appearance/disappearance but might be a question to ask in their forum.