Z55 rear shocks shot?

[Pandabird]

So my 2011 Tahoe has this thing with the rear suspension being all up in the air, I can in fact fit my head under the fender to check on the shocks. About 2-3 inches higher than the front. Checked the air bags after having it parked for a few hours and they feel soft. Turn ignition, wait a few seconds and they pump up just fine until you can barely press in a thumb so yeah the compressor works and there bags aren't popped at least. Actually they sorta feel like they don't have any major weight on them at all. Haven't tried weighing it down or towing anything with it yet. No warnings on the dash.

Third row seat was missing when I bought it, heard it has quite a bit of weight to it so I was wondering what I should try next. Load a few sandbags and jump up and down on the hitch? Any advice welcome.

Going to need to pull a 3000lbs trailer in about a month and I want to avoid catastrophic failure on the road.

 

[Joseph Garcia]

Are there any existing modifications to the rear suspension, such as lift blocks under or over the rear springs?

 

[Pandabird]

Are there any existing modifications to the rear suspension, such as lift blocks under or over the rear springs?

I'll crawl under it and snap a few pics tomorrow when it's daylight. It's actually not totally impossible it's been raised and it's in fact the front suspension "sagging". 20 inch rims, 275/55 tires. Got a fresh set of 275/40 for later just because it was cheap but the gap would become even more pronounced that way as is.
Edit:
Anyways here's a recent

Spoiler: sunset pic

to shed some more light on my issue.

Second edit: Rear shock struts: "BWI group 23487279" and front shocks "BWI group 20810264" I'll go have a read if it's OEM or not.
No signs of modification or tampering of rear springs.

One thing I noticed while under there was these thin rusty rods connected to sensors for each wheel.
Rear rods were shorter than the front; 2.3 inches compared to 3.9 inches in front.
I assume these are tied to the levelling of the car. I think I want to play around with these some as they feel they could easily be popped out and fiddled with. Wondering if it's safe though. At least I gotta check what the normal lengths should be.

 

[Pandabird]

Tried this today since I wanted to try bleeding the air anyways.

Kinda eliminates any possibility there's anything wrong with the rear shocks since they bounced just fine when completely depleted of air and raised just fine with some compressed air. Unless there's also the magnet woodo stuff in there I can safely assume a bigger shock has been installed and should therefore focus on the front shock functionality instead (noticed the sensor arms in front look a tiny bit bent)

Going to try simply jacking up the front and measuring how low both front wheels drop compared to eachother. That should rule out a seized front shock if nothing else.

 

[Joseph Garcia]

I never measured my front and rear height sensor rods to see if they are different lengths. but I assumed that they were the same length. They should not be bent, though.