I posted this back when I got my 2015 in the shake thread. The leaf spring clamps moved the speed at which the wobble/shake happened. It moved from something around 66 to 75. I was much happier as I drive 66 to 70 all the time on the roads around here. I tried in front, behind, very tight, slightly tight and everything effected it. Nothing made it go away. To tight the truck was rougher riding and the shake was worse.
Drive line was fine, u-bolt were tight but I had a lift kit on my truck. I changed those a few days after I bought it.
2015, RCSB, 4x4 3" Leveling Kit