How long do 5100 shocks last?

My rear springs are already getting pretty weak (just had them TSB replaced about 1-2 years ago) but I think that maybe my 10 year old 5100 shocks may be contributing to the slop. How often do you replace shocks for wear?

 

Visibility inspect to see if either are leaking. Get on the bumper and give it a good bounce. If it settles without jumping up and down several times they are good. If you feel like you are on a mechanical bull then it is time to replace.

The shocks should not provide lift, they keep the axle under control and from jumping out of control. The rear leaf packs are junk, you might be able to save them with an AAL or three leaf progressive pack.