The muffler heat shield may become loose on the muffler causing a rattle or popping noise. Our technicians tell us there is a kit available from GM to correct this problem.Google+
Car Problem Reports
GMC Yukon Popping Noise From Muffler Heat Shield
GMC Yukon Problem
Exhaust & Emissions Affected: V8
Average Mileage: 126,000 mi (115,000 mi - 132,000 mi)
Visitor, 2005 GMC Yukon, 132,000 mi
Loud rattling noise coming from under the rear of the car. Have not had it diagnosed yet, but souinds like this may be the cause. The noise is not constant. Usually at slow speeds. Independent of whether the car is warm or not.
upon accelaration, I hear the vibration of the muffler.