I think you missed the point....
I have airbags. I know I have airbags. I also know that my rear shocks look nothing like struts. You can't confuse them. There is a difference in "feel" for a rear air-bag suspension vs a rear "sprung" suspension. My rear shocks are shot, completely shot. But with the air-bags, it rides very much like a "sprung" suspension with decent shocks. That's one of the reasons I haven't replaced my rear air-bags. Multiple shock specs are different between air-bag shocks and coil-spring shocks.
It may be helpful to verify which suspension type you have in the rear. Unless you're the original owner, there is always a possibility that something was changed/swapped/retrofitted that you aren't aware of. I'm virtually certain you'll find you have air-bags as I have the same RPO code and I'm convinced it's for "ECAS" or "Electronically Controlled Air Suspension". ECAS 100% only applies to the rear suspension. The rear shocks intended for this suspension are different than those used with coil-spring suspensions. A cursory perusal of RockAuto's shock offerings suggests an inch difference in OAL and total travel in coil-spring shocks vs air-bag shocks.
If you find that you have air-bags under the rear, you'll want air-bag spec shocks. If you have coil-springs under the rear - likely the result of a retrofit - you definitely want coil-spring spec shocks.
I used to be an old-school offroader so I'm still a huge Rancho fan. Rancho actually offers their RS5000 shocks for this platform. They have 2 variants: one for coil-springs, one for air-bags. Different part numbers, different OAL, different stroke, and different damping.
I also recently completely rebuilt my front suspension including upper and lower control arms, and struts. The struts I got were the absolute cheapest that RockAuto carries. The difference was like night and day. New cheap struts beat worn-out top-of-the-line struts hands down.
As for "ZW7 means Nivomat shocks".... no. Not on a GMT360. No such animal exists. ZW7 means Nivomat shocks on the much larger and considerably heavier Yukon/Tahoe platform. The telltale sign for Nivomat shocks is that there is wiring TO THE SHOCK. The "air suspension" portion of a Nivomat shock setup is entirely self-contained within the shock. Nivomat shock suspensions also include lighter coil-springs. The coil-springs take the majority of the weight of the vehicle while the shock is used to level and provide damping.
Our air-bag suspensions are entirely different and do not include coil-springs whatsoever.... unless they've been replaced.