You won't hurt the truck by jacking if from any location where you can safely put the jack so it won't slide/kick out.
As 78buckshot said, make sure you have it properly supported before you get under it. Make sure you use truck size jack stands, the one's for cars might have the ton rating, but the tend to have a smaller footprint and are not as stable. Also, make sure you're on firm level ground.
Mike B
