you have to take the throttle intake hose off to get to the thermastat or sensor. but also the cross bead of rtv goes across the intake in this same area could be just a bad o ring that goes on the thermastat. if you put a new thermastat in it do not put one made in mexico in it as it will not open when it gets hot. and as for as i know g.m. build the ****lo's up to 2005 when they came out with the uplander.