springs and shocks ltz vs z71

i have a 2011 z55, ltz .(auto ride)
is there any difference in the springs and shocks vs. a  z71 ?
which is the softer ride ?
are the part numbers diff.?
does it make any difference which ones i get ?

thanks, Roger

Yes there are differences between a Z71 suspension and an LTZ. Not sure of the part numbers but there are many older threads about suspension work on this site.
basically the LTZ is an air controlled suspension that gives a smooth level ride and compensates automatically for heavy loads or towing.
The Z71 suspension is firmer and is more set up for off-road use and compared to a stock LT suspension it is firmer and feels "sportier" when cornering on the road.
You will probably generate error messages on your DIC if you do a swap from LTZ shocks to Z71 since it will throw the sensors off by not being connected. It is best to replace an LTZ shock with another LTZ shock to avoid issues.

thanks vaeagleav,
ok now the question is:are all the ltz shocks (oem) the same stiffness or are there different part numbers for different stiffness ?
is there just one oem shock that will work for a z55,ltz with no problems?

specific i guess .

thanks again, Roger

The LTZ shocks are all the same from GM.  They automatically adjust in real-time to create a nice ride.  The rears also auto-level for you.  There was a lot of debate about aftermarket vs stock on this topic.  I came down on the stock side.  A lot of engineering went into this system and it is worth its weight in gold.  If you swap in new stock shocks, the ride will blow your mind.  I couldn't believe the improvement. 

If you look around you can find autoride shocks on Amazon and elsewhere for FAR less that what the dealership is asking.

I wrote a thread on this a while back:
http://www.chevyavalanchefanclub.com/cafcna/index.php/topic,142025.0.html