After 3 weeks of listening and many trips to the mechanic of an increasing squeek from the rear suspension, today i checked the shocks and found the rear left shock upper nut was loose, when at the mechanic they lifted the truck and had the wheels on the air and thats why they never found out that the nut was loose, I rememberd that the 2000 F-150 rear shocks are longer and that I had to use the OEM bushing due to the shock being shoter and the bushings supplied were too thick, well this time I thighten it so hard and sprayed undercoating on the thread to be sure that it didnt loosen again, I had never expirienced this of shock before, make sure when purchasing an aftermarket shock that you receive the right one specially for the 2000 model and on, I have the Rancho RSX.