Hesster

https://diyautoservice.com/best-shocks-for-gmc-sierra-1500/

You may be right on that. My last GMC had the Rancho shock option and it rode much better than my current SLT https://www.summitracing.com/parts/ran-rs55100/make/gmc/model/sierra-1500/submodel/slt/year/2020

I think it does have suspension adjustments, as a cable runs to the front shocks. And this: CONTINUOUS DAMPING ADAPTIVE RIDE CONTROL The system monitors input from both the road and the truck in real time to help deliver a smooth ride. Every 2 milliseconds, active dampers continuously adjust both rebound and compression forces to counter heave, pitch and body roll. Stiffness rates also change when Sport mode is selected, or automatically when it senses heavy trailering or large payloads.

That is some great input. So maybe it is a Spring/Shock tuning thing, as I imagine the GM developers tuned the ride with a load, so there is a trade off. It does have selective ride (3 position knob), and I find ironically it rides better on the "Off Road" harshest setting. But that only controls the Front Shocks, the rear are conventional. Go figure. I know my last truck had "Rancho" shocks, but I would think they are harsher than the one's I now have. I do still have a "Water Bladder" from my 1st 2wd Truck I owned. Maybe put that in, but then it compromises the use of the Bed.

I pulled the trigger and purchased my lease on a 2020 Sierra SLT, given a new lease is ridiculously expensive. But - the ride sucks unless it is loaded up. Looking for a high quality Rear Shock replacement recommendation?