My Zuk is in my sig.  I am not entirely sure, but it feels as if the original shocks were used even though it was lifted 4"??  Is that possible?!  I took the two rear ones off and replaced the rubber mounts since they were cracked and falling apart.  But these shocks seem awfully wimpy.  Going down a gravel road is horrible and running over even a slightly big rock at speed causes it jar/slam the whole vehicle.  It's not horrible but it's nowhere near comfortable.  What is a good replacement set of shocks for both front and back?  I'm leaning towards an adjustable set so I can dial it to more firm on the trails and softer on the roads.  What options do I have?

I doubt that we can answer your question with just the information you have provided. 

There are a number of different ways to do a four inch lift on a Samurai and since we don't know how yours was lifted we can't tells you what shocks can be used with any degree of accuracy.

You can do a "spring under" which is when the axles are moved from their normal location above the spring and fitted under the spring, stiffer springs is another option, as is a combination of body lift and spring lift - the stiffer springs could be aftermarket springs designed specifically for a Samurai or they could be springs from another vehicle (I think YJ Jeeps springs are popular) which might require moving the hanger locations on the frame, and if we're talking fram modifications then there is the possibility that the shock mounts may have been relocated...

I'm sure you get the picture - without the details we have no idea where you stand.  I'd say it's highly unlikely that the original shocks were refitted, not with a four inch lift, at least, not unless it's a four inch body lift, which I doubt it is.

Where you're going to need to start is to remove the existing shocks and then find a way to jack the axle so that it flexes the suspension so you can measure the shock length needed at full compression & extension - one way is to use a fork lift to pick one wheel up until a second wheel just lifts - at that time the wheel you're lifting will be at full compression and the second wheel that has lifted will be at full extension.

Once you have open & closed dimensions, you're going to need to address valving, which is an aspect I cannot assist you with.

By the way, regardless of what vehicle you're driving, anything short of a hovercraft that runs over "a slightly big rock at speed" is going to jar/slam the whole vehicle - that's the laws of physics.  The Samurai is not a comfortable vehicle (I'm inclined to say there is no leaf sprung vehicle that is) and that four inch lift probably doesn't help matters any - it's a short wheel base, solid axle, leaf sprung, light truck and it's going to ride like one.

One last comment - what load rating are those tires, and what pressure are you running in them?  Remember, this is a {i]light{/i] truck.