Here are some skins dff , you can change their id code and replace them wiith any skin of your gta3.img .
You can use the GTA IMG TOOL app , but I recomend you to use Alcis IMG editor for PC, because sometimes in Android doesnt install the skins correctly. I'll leave you the link of my video, there you got them installed: https://www.youtube.com/watch?v=0t31v4AyvKI

(sorry 4 bad english xd)