What is the purpose of the top clip that actually goes on the rear caliper itself? I didnt have one before, just put a new caliper and bracket on and now it is rubbing the rotor when i drive likely due to rust. Do i need it ? I looked on the forums and never really found an answer.

 

That is listed as an anti rattle spring in my GM manual , I think it would also help keep rocks and road debris from possibly getting into the caliper. I'm sure your truck wasn't the only one running around without one , but I would want one there if I could make it work.

 

These little dohickies? Yes, antirattle springs. Not really necessary, more of a thing that keeps people from going to a shop saying "my car is making a strange noise" that said person doesn't know what the sound is... It'll let the pads flop around a little in the caliper, but isn't going to cause anything else.