Suspension Noise problems of the 2002 Ford F-150

My truck that I bought brand new is a 2002 Ford f150 supercrew that I take very good care of. The truck has just over 64,000 miles on it. On occasion I do use the truck like a truck and tow a 19' boat with it and I use it to pick up lumber etc. . . Three weeks ago I began to hear an odd metallic sound from the back of the truck while going over bumps in the road. I climbed underneath and grasped different components of the suspension and drive train and pushed and pulled on them expecting to find something loose. I didn't find anything. The next day I was driving down the road and I heard a very loud boom! I pulled over and again looked at the rear end of the truck and found that the mount that holds the rear leaf spring to the frame body had broken rather violently and sent the end of the spring with half of the mount thru the underside of the truck bed. I was able to limp home. I brought the truck to the local body/ frame shop and the owner told me that he has been seeing alot of these lately and it is a common problem. After inspection he found the other side was equally rusted and ready to let go, which concerned me since that is the side with the gas tank on it. In his expert opinion he believes that Ford had underbuilt the leaf spring mounts and that is why they are begining to fail on trucks that are around the age of mine. The frame is safe and solid enough but the mounts for parts of the suspension appear not to be. I am fortunate that I was not towing my boat, or that the bed was not loaded and I was not driving more than 35 mph when the mount let go. I don't know what might have happened if I was on the highway at 65 mph. The repair cost $659 and in my opinion it is something that should not have failed considering the age, condition and the low miles I have on the truck. If this truly is a common problem that Ford f150's like mine possess than it is only matter of time before the failure of these parts cause a bad accident.