First you need to download "Gunrunning DLC's Clothes to SP 1.0":
link: https://www.gta5-mods.com/player/gunrunning-dlc-s-clothes-to-sp
in order for this mod to work for franklin and trevor.

After installing the Gunrunning DLC's Clothes to SP 1.0, 
move the files to the following folder with OpenIV

If you want the Leather Jackets and Black shirt for Trevor:
C:\Program Files (x86)\Steam\steamapps\common\Grand Theft Auto V\mods\x64v.rpf\models\cdimages\streamedpeds_players.rpf\player_two

If you want the Leather Jackets and Black shirt for Franklin:
C:\Program Files (x86)\Steam\steamapps\common\Grand Theft Auto V\mods\x64v.rpf\models\cdimages\streamedpeds_players.rpf\player_one

