Installation (REPLACE):
1. Copy the contents of the vehicles.txt file to the path:

Mods - update - update.rpf - common - data - levels - gta5 - vehicles.meta (search and replace the FLATBED content inside the file)


2. Take the vehicle files (flatbed.yft, flatbed_hi.yft, flatbed.ytd) in the Replace folder, and move them to the following directory in your mods folder:

Mods - X64e.rpf - levels - gta5 - vehicles.rpf (Drag and drop)

* If it doesn't work try the other way:

Mods - Update - x64 - DlcPacks - Patchday22ng - dlc.rpf - x64 - levels - gta5 - vehicles.rpf (Drag and drop)

or the last patchday you have
3. Copy the "scripts" folder to the GTAV directory.

Installation (Add-On):
1- Take the Cargo815PMESP folder from the Addon folder and move it to the following directory:
Mods - Update - x64 - DlcPacks (Drag and drop)
2- Then go to Mods - update - update.rpf - common - data edit the dlclist.xml file and add the line:
dlcpacks: \ CargoPMESP \
3- Copy the "scripts" folder to the GTAV directory.

Credits:
GodAlucard