[Rev]

Please forgive me for getting down to basics. Are the front wheel bearings adjusted properly, no looseness allowing wobble? Lug nuts all tight?

The rear end should not be lower for any reason unless you added lowering blocks or springs with a modified "eye", i.e. mid eye, reverse eye options. New springs normally raise it some from the old sagging leaf springs position. Rear shackles also need to be in good shape, but that usually hurts cornering more than anything.

Balancing a drive shaft needs to be done at a drive train specialty shop. Now would be a good time to replace u joints if they are 5 yrs. old.

Still, there must be something way off to cause shaking at speeds 10 mph and above. I'm not sure what that could be.

Rev