We had a 3008, in my opinion the thin, lightweight frame is the big reason because of the diagonal flex. We used xchocks between the wheels in addition to the 4 frame mounted jacks I tried 4 additional screw type RV jacks, 2 at bumper and 2 at front at front of axles. I didn't think jacks under the slides was a good idea. Somewhat improved but still not great. The Yorkies jumping off the bed would still shake it... I believe that same flex is causing the cracks in the walls. Too much length to be"half ton towable"
2015 F350 4X4 Crew Cab Lariat
Sunnybrook Titan 30FKS