Rockstar tried to kill off the vintage HVY Brickade to no avail. That is because it is officially Keter Class.

Installation:

1: Install this mod:
https://www.gta5-mods.com/vehicles/chuff-security-livery-for-hvy-brickade-add-on-livery

2: Extract the "avan_body.dds" texture

3: Add it to "F:\SteamLibrary\steamapps\common\Grand Theft Auto V\mods\update\x64\dlcpacks\brickade2\dlc.rpf\x64\levels\gta5\vehicles\vehicles.rpf\brickade2.ytd" using OpenIV with Edit mode enabled