I bought a used GMC Sierra 1500 Extended cab 4x4 in August of 2008. The speedometer was working when I drove it off the lot but on the way home I passed a local police car and glanced down at my speedometer and it was sitting on zero. It worked from time to time after that but now it spends most of its time sitting at 70 m.p.h. while the vehicle is parked andsitting still. I understand that GM was sued because of this problem and I called GM in Detroit and the person I talked to informed me that only the 2003 and 2004 Chevies and GMCs had thos problems. I beg to differ with you sir but my 2005 Sierra has this problem as well and the dealer wants $650.00 to repair this problem. I think this is GMs problem and not mine, when a speedometer doesnt work it is extremely dangerous. I dont know if the cruise control will work while the speedometer is messing up or not I know it works when the speedometer does work which is not very often. I think GM needs to stop patting themselves on the back for so called repaying the loans to the US Government and fix some of thes problems with thes vehicles before someone is tragically injured or even killed because of this problem.