I've had the very same 5125's on my junk since '05
neither have leaked.
I have a 2.5" lift....
and use 8" and 8 1/2" travel shocks
The 1/2" difference is due to the staggered upper mounts.
I'm gonna guess your shock travel lengths are incorrect
and that the shocks are bottoming or extending too far.
* I thought the stock shocks (oem) are 6" and 6 1/2" travel
Yeah its pretty fool hardy to lift the rear of a 1st gen ANY amount without a shock upgrade...