the coil over type that s13's use does not generally have re placable shocks, infact im 90% sure they cant be. SOME shocks can be rebuilt however, but not all.
for a s13 front end into a 86 you are looking for anything that is base height adjustable at a minimum, because the car will be VERY low at the front if you do not. other wise dampner adjustable shocks are a plus as well.
also they do nto bolt in directly, so have you given any though at to what struts tops, LCA, tie rods you will be running?
-dan