Rattling From The Front End

[cammedLM7]

This question is for the GM tech or anyone who can answer this

 

I have a 2002 silverado 2wd and going over bumps or washboard type roads, there a rattle or a clunk and i thought it was a really bad I-shaft and i did take it to the dealer and they replace the shaft and the noise is still there, and i can duplicate it by press the gas and the brake pedal really quick and even the tech heard it and he duplicated as well but had no idea what it was, so i drove the truck to my dad's house and jack the truck up and pulled the front wheels off and i couldnt believe how loose the calipers was, i mean they were tight and such, but i can move the caliper within the bracket freely and the front pads were about 50% or a little less and so i check the rear brakes too and there fine no problems, and so i crawl under the front of the truck just to make sure it wasn't anything else and i did see so grease leaking from the left front inner tie rod boot or bellow but i wouldn't think it would be a inner tie rod unless im wrong so my question is, is there something wrong my calipers? even though my front pads are about 50% or less do i need new ones? please someone give me some advise about this issue cause its driving me crazy.