Use OpenIV, navigate to:
D:\Grand Theft Auto V\mods\update\x64\dlcpacks\lexlfa10\dlc.rpf\x64\vehicles.rpf
open lexlfa10 and click on the Import button on the top left corner (+)
navigate to this folder (where this readme is located) and select the lexlfa10_sign_2.dds
click import and save
done!