Shaking over rough roads/bumps

[81GMCSierra1500]

Hey!

I'm just narrowing down on little issues (finally through all the major stuff, yay!) but one thing sticks out like a sore thumb... it shakes like a leaf over rough roads or bumps, it's not just like a front end wobble, the whole frame "wiggles" over rougher roads, it's mainly felt everywhere, except in the steering wheel... I've got a hunch it's something wrong with the rear suspension... Shocks? broken leaf spring? What are y'all's thoughts?

[Cabnchassis]

Check all the cross-member connections. On my C&C I was getting some weird vibe and clatter, tranny cross-member had worked out both bolts on one side. Bushings in the leaf springs could just be completely gone too.

Look at the short fat leaf on the bottom of the stack, how well is it aligned with the other leaves? Do your shackles look ok?

[81GMCSierra1500]

Ill take a good close look in a bit. thanks a million for those tips! I'll let you know