With me, it's not appearance but performance. If it starts to sag in a corner or something is visually busted, it's time for springs. If it starts getting wobbly and bouncy on one corner or more of the truck, it's shock time. Mine is starting to get kinda bouncy lately, and doesn't sit level from front to rear. I think I need both shocks and springs all around.
My oil line fix
My 100k stopped odometer fix
Brace for impact, I'm in a "modifying mood". Massive thread count inbound.