I also had a 2000 and used Briar Hoopers FP gauge. The best place to test and the easy place is on the VP44. From the drivers side look over the top of the battery at the side of the VP44. You will see a black cap attached to a port. That is where you screw in the fitting for the FP gauge. If you don't have a Service manual get one. You can order one for your truck by calling 800-890-4038. Even though I am not a great machanic, it helps to have the service manual.