Shocks & Struts.

Quick question when do you know when the shocks require replacing.

Meaing I am not to familiar with the Denali ride so I would say it feels good but every now and then she rocks like a boat and I would say that isn't normal, right?

So while inspecting her before purchase I assumed I would have to replace them anyway. They look like the stock DeCarbons (or whatever they are called) so I figured I would go with Bilsteins..

Thoughts/Suggestions?

Update:
So looking at AZ...I can't find the Z55 AutoRide Shocks.

Still looking.

Ok so I was searching the forum and found a few things...

http://www.tahoeforum.com/showthread.php?t=1911&highlight=Shocks

http://www.tahoeforum.com/showthread.php?t=2050&highlight=Shocks

http://www.tahoeforum.com/showthread.php?t=1676&highlight=Shocks

So I apologize for the repost. So I am still looking for a good answer.
Looks like quite a few of us are.

I have the original direct fit shocks for z55 autorides! Let me know if you're interested!