I have a 2005 Z71 with over 100,000 miles.  I am haveing a stearing issue that happens when you turn the wheel left or right quick.  the stearing wheel feels like there is no power steering in the truck but I have had 3 power steering pumps put on and then we found a thread that said you had to replace it with a certain pump.  ao I did that and I still have the issue. any help would be great.  

I do not see a new steering box in this problem. They due wear out and can leak boost internally with age and usage. Also if truck is lifted and has big tires this increases steering loads on box and can shorten its life. With stock tires and lifts steering boxes can go a few 100 K miles with no problems usually but with lifts and big tire the life span can be reduced. Basically this means there is no free lunch with lifts and you can pay a price with shorter component life.  

I dont think you needed to replace 3 pumps as it sounds from your descripstion...the subs, tahoes, and pups all have a steering wheel position sensor at the base of the steering column that go out and every now and then when you turn your wheel to lft/rht it seems very hard,especially at lower speeds. may happen over bumps too. (doesnt happen all the time, but its annoying) its a 65$ part at the dealer. so I would look into that and quit buying unnessary pumps.  

Tahnks for the response to my question I was unaware of the sensor you mentioned.  I will try that.  I have not had to pay for but for one pump do to they wer still under warrenty.  how do you get to the sensor.  

they are at the base of the steering column next to the fire wall, (they were under the hood on the older rigs/95-00) and may have moved them inside cab. give the dealer your vin and they can tell you for sure. but you have disconnect the shaft and unplug the sensor, cause it slides over the shaft.  

What you are talking about though it something that reduces boost at speed to give you more road feel. As stated this would be pump independent. Not convinced it is this switch though (I could be wrong) but it is worth checking it anyway.  

my dads 96 k1500 6.5td had the same feel in the wheel while turning lft or rht and over bumps. especially railroad tracks. the wheel seems free turning lft then it felt like a hard spot that you had to put more muscle in the turn then it would be free again. the sensor was bad. replaced and never had the problem again (dont know if it had the problem later in life as he sold it for a newer pup)and I believe the 02 sierra k1500 he bought had the same problem but it was covered under warranty.