My steering makes a howling/groaning noise when turning full clock. And the steering seems harder to turn. How do I diagnose if it's a pump/steering box issue? Or both?

 

In my '03, with same symptoms, it was the PS pump.

When you have an opportunity, click on the "User CP" link up above your initial post, and then click on "Edit Signature" if you want others to know what truck you might be asking questions about.
Back to morning brew . . .

 

Thanks for the reply FMB. Maybe I will do a fluid change to see if I can extend its life a little longer.

 

You can also do a mixture of 1/2 ps steering and 1/2 STP oil treatment. Or start out with a lower ratio of STP if you don't feel comfortable.

A few of us 1st genners use this method to improve the feel of the steering system in our old trucks. When I rebuilt my steering system (rebuilt gear, ps pump / hose) I went this route on the advice of the Gear rebuilder

Power Steering Services, Inc. - www.PowerSteering.com - 1-417-739-9010 | Modern Steering For Classic Cars

 

Thanks for the tip NJT