I got a nice used lightning suspension and am going to install it, but I am thinking I should replace my lower control arms while I'm in there. The truck has 107k miles on it. How long do the lower ball joints normally last?

Also, I was checking a few of the ford parts sites online and noticed that the lightning had different lower control arms. I think I read somewhere they had stronger ball joints. Anybody know?

 

Only differences I know of on the front suspension are the springs and a steering stop to keep the tires from rubbing. You can replace just the ball joint on the bottom. Upper arm has to be replaced. You'll get a variety of answers on ball joint life on here. Some guys have had to replace as early as 25-30K. Make sure you get the ones w/ fittings.
And post some pics when you're done