jk,
  Consider yourself  VERY, VERY, VERY fortunate with your KYB shocks!!   I
has KYB shocks on all four when I got the car in 2000 and decide to replace
the rears when I decided to install new springs to lift the rear end. The
new KYBs lasted about 2500 miles before the top threaded shaft snapped
apart.  Happened on both sides.  Fortunately, I had kept the old KYBs which
were still in pretty good shape. I've run the old ones another 50,000 miles
with no problem.

Others with XJ40s have had the same problem with  the tops of the shock
snapping off. The supplier took them back no questions asked AND with the
comment that KYB had a lot of these shocks being returned. Hopefully, with
your experience, KYB got the manufacturer's defect fixed.  I'll stick with
Boge or Bilsteins -- or even Monroe for the same price as the KYBs

Webserve

Webserve