I also replaced my headlights and side markers... I had the tedious job of aiming also... park about 25 feet away from a wall, preferably at night... take the mounting tabs off, adjust the three rotating screws or adjusters each independently and place light back and check for proper alignment. once you think they are aligned, put tabs or locks back on and see... May have to repeat this a few times but it will become easier after a few times...