Installation: 

1: Install this mod: 
https://www.gta5-mods.com/vehicles/volkswagen-beetle-1974-template-add-on

2: Using OpenIV, access C:\Program Files (x86)\Steam\steamapps\common\Grand Theft Auto V\mods\update\x64\dlcpacks\beetle74\dlc.rpf\x64\vehicles.rpf\ and import the "VW_sign_5" texture into the beetle74.wtd file. 
N.B. You will need to use "Edit Mode". 

3: Done.