When to replace shocks?

I have a 2013 DBCB running heavy front & rear OME with their shocks, set up is 4.5 yrs old with about 90k miles on the set up.
Shocks aren't leaking but how do you tell when it's time to replace them?

 

The handling goes to crap. Ride gets bouncy.

 

when they are leaking

 

The suspension is stiff enough can't feel any change handling is same, great OME ride but wonder when to replace.
I had the same problem on my FJ60 so still couldn't tell, the ROT of pushing down and watch the rebound doesn't work with 4x4s

 

Same question. I am at 65k miles and 8 years

 

I called Sierra Expeditions were I bought the OME set up 5 yrs ago.
He said they should be replaced at 65k miles.
So I'm a little over due for new shocks.

 

I replaced mine at about 125,000 when I noticed odd tire wear. Mine never leaked, but were STIFF and impossible to move by hand once removed. Instead of mushy ride mine had gotten very harsh but it was so gradual that I didn't notice. I never noticed any real difference in ride until after mine were replaced. There is a railroad crossing that I regularly use and after the new ones were installed that crossing became much more comfortable.

 

Sounds like my issue too.