I had my wife's 2005 Regular Cab 4X4 in for the fifth (or more) time for squeaky rear springs (77,500 miles). Past repairs have included lub, new silencer pads, new springs, more lub and I'm not sure what else. According to the service manager at my dealership, this is still an ongoing problem even in the 2009's. There is a new set of pads that are available that are supposed to be "the fix" according to the engineers at Toyota. No TSB out on it yet. It's that new. I had a set installed yesterday. Hope that it works this time.
Tom