I have just had a re-built 6.5 motor installed in my 97 GMC Sierra, motor sounds beatiful, but i am now getting a noise like an exhaust leak when i am
idling under load and when accelerating, the guy who put it in says it could be the turbo on it's way out, at times it almost feels like its a transmission probleml, I can feel vibration on the steering wheel and brake. Any idea what this could be?

Thanks,
Nieco.