I have a 1983 GMC Sierra 3500 4x4, and when I get moving down a rough road it acts like the motor is spinning inside the engine bay. The other day I tightend everything up that I could see might be wrong with it, and I am at my wits end. I don't know if I need to replace the springs or replace the shocks. Everyone tells me replace the shocks but the springs are bending backwards, there past flat. I can see where the bump stops are hitting the leaf springs and I don't know what to do? So, I am asking for help.