Mine were gone after about 20k. Bear in mind that the day after I bought my 4Runner I went out and put 265/75 BFG A/T TA's on it which increased the unsprung weight considerably and also drove about 4k miles on old mining and forest service roads.

OEM replacement is OK, but when I replaced mine I went with a Gabriel HD model which was a nice change. KYB and Bilstein also offer direct replacement shocks.

Sounds like your have had it.

Mike