Where is the egr valve on 2000 5.9 cummins engine?

On a 2000 5.9 Cummins engine (found in Dodge Ram trucks and other vehicles), the EGR valve is located on the passenger side of the engine, near the back. It's typically mounted on the intake manifold. You'll likely see a vacuum line connected to it.

Because of the engine's design, getting a precise location without a picture of the specific engine is difficult. However, the passenger side and rear-ish location is consistent across that engine generation. A repair manual or a diagram specific to your year and model truck will give you the most accurate location and visual confirmation.