They last about as long as it takes the paint on them to dry 
You don't know what you're missing running the stockers forever. It's one of those things you didn't know what you were missing until you experienced something better. Try a set of Bilsteins and you'll see what I'm talking about. I DO use my truck daily, so ride comfort and handling (yes, 3. 5 ton trucks do handle better with good shocks) is important to me.
Just my viewpoint...

You don't know what you're missing running the stockers forever. It's one of those things you didn't know what you were missing until you experienced something better. Try a set of Bilsteins and you'll see what I'm talking about. I DO use my truck daily, so ride comfort and handling (yes, 3. 5 ton trucks do handle better with good shocks) is important to me.
Just my viewpoint...