suspension issues... do i need new shocks?

I have a '97 4Runner SR5 w/ 98k miles. I think the suspension needs some work. When I go over small dips or bumps, the rear hits w/ a thud and has very poor recovery. I'm trying to determine if the problem is w/ the shocks, suspension bar, springs or something else.

Any feedback is appreciated.

Measure the distance from the top of the wheel well opening to the ground, both in the rear and front. The rear tire should be about the same distance from the top of the wheel well to the ground as the front tire, maybe an inch or so higher in the back. Also both sides of the front and back should be about the same as each other. With standard fairly new tires on 16" rims, I have about 34" clearance in front and 35" in rear.

If the height is low, you have weak springs. If the rear end bounces more than once when you jump on it a few times to get it in motion, then you need new shocks. Could be either the springs or the shocks or both, depending on the results from the measurement.

The rear springs on 4Runners are notoriously weak, causing the well known "sagging butt syndrome". The "thud" you hear is probably from hitting the bump stops due to weak springs and the "poor recovery" is typically worn shocks. Factory shocks usually don't last 100K mi. on any vehicle.