How to change belts on 2006 Freightliner?

How they're routed depends on your engine... Detroit Diesel, Mercedes-Benz, Cummins, and Caterpillar engines were available for that model year.

First, you make sure you have a belt diagram.. if there isn't one available, you draw one.

Taking off the old belts.. just cut them. If you're replacing them, it doesn't matter if they're intact or not.

Putting the new ones on, you have to route them through the engine fan. Put about half of the belt through the engine fan, rotate it, pull it back through.

Then, you route the belts through, and, as you get to the tensioner pulley, you pull up on the tensioner to provide slack to allow you to do this.