Really Noisy Suspension

[gator2511]

My 72 K10 sounds like a bucket of bolts coming down the road. Its one of those things that came on gradually so I didn't get irritated about it for a while. The noise seems to be coming from the springs. Its like a metallic slapping noise. Seems to happen on small bumps as well on the big ones. I hear it from the front and rear. Do these 4wd springs do this when they age and wear? I don't remember this much noise in the past. I have replaced the spring bushings and checked everything for being tight but can't find anything loose. The shocks and bushings seem good and there is no slack or play anywhere. Did Chevy put anything in between the leafs to dampen the spring noise? The glovebox door label says I have a heavy duty spring on the front.