I drive a 1991 Pick up and the bounce off of speed bump, small pot hole, or uneven roads just hit very hard. I want to know of its possible that my shocks are seized up, is the vehicle just too light, or is that just normal. Ive had the truck for a week now but the shocks do look old.

 

How far is your bottom bum stop from upper bumpstop? Your truck may have the typical rear-end sag.

Take shocks out/ Easy and good practice for when you remove and replace. IIRC, it uses 22-mm socket/wrench.
Compress it by hand and see if it extends back.

 

okay thanks ill look into that, and also how do i know if my pick up is lifted? Does that matter when buying new shocks?

 

Bad shocks tend to bounce and just lose the ability to absorb any shock.
your probably " bottoming out"
Rather than being locked up.
If your rig is lifted you can look to see if there are any blocks under your leaf springs.
Pics might be helpful...

 

I've seen shocks go bad by fully extending them and they "lock" fully extended. Twice on those awful 3 lettered german cars. Lifted them up to do an oil change and when I put them down the shock absorber no longer compressed. Buuuut these trucks do ride pretty stiff. And the above comment is correct about shocks usually stopping dampening when faulty. You get bounce that goes on for a long time. To test, put your knee on the bumper and bounce the vehicle up and down a couple of times. When you stop the vehicle should bounce one time and stop. I.e. When you bounce down and get off the bumper it should go back up and then to ride height and stop moving.