I have a 2008 4x4 standard trans and all stock. The exhaust break started to make a slight squeal under heavy loads on the heals. Now it is screaming. Truck has little over 200,000 miles on it. All services have been performed at the proper times. Any suggestions would be greatly appreciated.

 

Make sure the bolts that hold the EGR cooler to the manifold are tight. Sometimes they will come loose and the resulting exhaust leak will make a squealing sound.

 

I agree with Gatorama. It is very likely that the rear cooler gasket has torn or isn't tightened down all the way, so it is leaking between the mating surfaces.