used for example, is my 1980 datsun 200sx.

the theory:

similar to how your vehicle sits on gas charged shock absorbers, so sits your bumper
on gas charged shocks as well. depending on who you talk to, this is called a bumper
shock or bumper absorber. the bumper shock is mounted between the bumper's
core bar and the vehicle's frame. the bumper shock compresses and absorbs much
of the impact experienced in low speed collisions. with dual purpose, this prevents
damage to the bumper itself and also to the vehicle's frame.

warnings and materials:

because these absorbers are gas charged you want to be careful when handling
or removing one which has been depressed. if the shock were to suddenly return
to its original position, it would do so with force. approach it with proper caution
and you should have no issue.

the setting : an ample work space
the tools : ratcheting socket wrench, a 17mm socket and a 10mm hex driver socket.

the bumper bar is mounted directly onto the shocks via one 10mm hex bolt per side.
the bolt runs through an end piece which mounts at 4 points and is removable from
the bumper bar. for you to be able to remove the bumper, it should only require the
removal of the 10mm hex bolts and not the end piece itself.

get underneath the bumper, and using your ratchet with the 10mm hex socket,
locate and then loosen the hex bolts securing the bumper bar to the shock absorbers.

when you remove the hex bolts, remember that if your bumper is like
mine, there will be wiring for the turn signals and running lights which you will have to
unplug from the harness before fully removing the bumper from the absorber mounts.

once the bumper is removed, observe the shock positioning, you should easily be able
to recognize which side is off by the position of the shock body in the mount.

some pictures shown for reference of damage :

due to the slight difference in length between the 1980 and 1983 bumper shock
I will be replacing both sides as opposed to just the damaged one.

locate the four 17mm bolts securing the bumper shock's flat mount to the vehicle frame.

using your 17mm socket remove all 4 bolts, keeping your face out of the shock's
line of fire.

to replace is simply reversing the removal procedure.

and here it is with the bumper back on, shown against the original for reference.

hope this helps someone, good luck!