^^^Thats about it. When the ride is no longer satisfactory, your truck bounces too much after a bump, your front end starts feeling "loose", and the afore mentioned 2 bounce test.
Replace your shock with any factory replacement part you like. Depending on what kind of ride you want, there are upgrades available, but if you just want a stock ride, put on a stock shock.
BTW, the shocks will do nothing for saggy springs, they don't change the ride height.