UPDATE:
I ended up purchasing the following rear springs since these are cheaper than the "Original OEM" part 23154237 from my previous post.
These ones are
Moog 81071 Coil Spring Set
My understanding is that 81069 are stiffer for pulling trailers, but even though I intend to pull my small boat once in a while I preferred the somother 81071.
I just installed the rear springs and shocks, and my wife is like OMG!! (the Tahoe PPV is my wife's car). With only half of the parts installed is already like night and day in terms of the smoothness of the ride. We had a banging noise somewhere under the plastic cover under the back seat or 3rd row seat that was driving us crazy because it would bounce on every little bump on the road. I've spent a lot of time looking for what that was with no luck. Then studently, with the rear parts installed, that banging noise is GONE! I could not be any happier already. I'm even questioning if I still need the new FRONT parts installed. But since I already have them I will still get them installed. Since the front will need alignment after the installation I decided to have somebody else do the installation and the alignment at the same time for me.
I did install the rear parts myself in one afternoon, it is really easy to do, as long as you have the car high enough for the rear axel to drop down enough so the new springs fit right in. In my case I didn't crank the jack high enough and the tire touched the ground so it didn't allow the axel to drop enough, so I had to use the spring compressor to make the new spring fit in the space (I could have removed the tire, but I didn't). Then for the other side I did lift the car high enough, the axel dropped enough and the new spring went right in. No problem at all.
Just make sure that if the break hoses are not long enough you will have to detach the holder from the axel, so the axel can drop enough.
Another thing that I wanted to mention is that the height at the rear gained about 2.5 inches with the
Moog 81071 springs I purchased. I was not intending for that to happen, I was hoping the height would remain the same, but in the end my wife hasn't even noticed the difference in the height, so I'm not going to complain. But just be aware if you don't want your height to change then you need to purchase different springs. I think the shocks are ok either way.
I will post again when I have the front struts installed and see if that gains additional inches in height.
NOTE: When I purchased the rear springs I did notice that the new ones had more coils per spring than the existing ones (about 8 vs 5), but I figured that that was the reason the ride would be smoother since more coils allow the spring to be less rigid and compress more smoothly. Also, the new springs were about 2 inches taller than the old ones when compared uninstalled side to side. I was kind of expecting that the additional coils would compress and keep the car at the same height. However that was not the case and I ended up gaining the 2 inches or so in height.
So I was thinking that if you don't want any additional lift, maybe you have to find springs that are the same height as the old ones.