1. Download SPARK. ( Use SPARK, not SPARK CS ). When SPARK is opened, click file - open - your game installed directory - models - gta3
2. Drag .txd file to SPARK. 
3. Save and exit.
Enjoy!

Make your own paintjob! go to to learn how to make one.  https://www.youtube.com/watch?v=LuBWqBCPwCU 

Thank you for downloading this Paintjob!