On my '99, there is a screw on top and on the inside (toward radiator) of the light. It takes a small "star" driver to adjust them.

CR

 

To lower the beam you want to turn clockwise the screw at the bottom center of the headlight, it takes a T-15 torx. A little goes a long way, try half a turn at a time.

 

Make sure the torx drive is seated all the way in the aiming screw and that you hold good pressure on it or you'll strip the torx head out of the screw. You'll need to shine the lights on a wall from about 25 feet (according to the service manual). I couldn't get mine right at 25 and went a little further out and now am satisfied with the aim. 25 feet will give you two distinct ovals to aim with so start there.

 

I hear what ya say Alan. Cept you like to shine the lights high lefty, stead of low righty. Must be to much boat riding. All the ups and downs?

..Preston..

 

I hear you Turbo Thom. Long time no see. All this bad weather here makes me afraid of having any lights at all. I hate to have a spot light on and see a wave go by the boat at night. Scares me.

 

Here you go. Good details can be found here:

https://www.dieseltruckresource.com/...%2A+AND+aim%2A

Maybe here too:

https://www.dieseltruckresource.com/...ht=headligh%2A