I own a 2000 GMC Jimmy and everytime I go over a speed bump, pot whole. etc. It...

[Jessie]

...feels like my rear axel swervs? It feels like my rear axel jumps up and then swerves side to side. What does mean? Do I have to get a new suspension system, or a wheel alignment?
It feels more like my rear wheels swerve side to side.

 

[thugtwin1@sbcglobal.net]

sounds like shocks are just flat shot, and need to be replaced.

 

[Molson02536]

...feels like my rear axel swervs? It feels like my rear axel jumps up and then swerves side to side. What does mean? Do I have to get a new suspension system, or a wheel alignment?
It feels more like my rear wheels swerve side to side.

Time for new shocks and may be sway bar end link bushings. One of the best shocks you can get for your Jimmy is the http://www.monroe.com/products/reflex_truck.asp. I am running the Monroe reflex shocks on my jimmy and have been pleased with them, it give the Jimmy a more firm ride like a Camaro or Corvette around corners.

If you don't like a to stiff of a ride, you can use these http://www.monroe.com/products/reflex_monotube.asp which is more forgiving but still firm when needed.

Good luck and keep us posted.