Installation:

1: Install this mod:
https://www.gta5-mods.com/vehicles/1959-cadillac-eldorado-biarritz-convertible-add-on-lods-template

2: Extract "eldorado59_sign_6.dds"

3: Add it to "C:\Program Files (x86)\Steam\steamapps\common\Grand Theft Auto V\update\x64\dlcpacks\eldorado59\dlc.rpf\x64\vehicles.rpf\eldorado59.ytd"

Credit for 1959 Cadillac Eldorado car goes to OhiOcinu & GreenAid