It depends on what you mean by "front drive train" noise.
If you have the auto transfer case, (you should have
one button on the dash that says "auto4hi") they do
tend to be noisy in both the auto and the 4hi position.
Especially on high traction surfaces. Usually, tho, you
will notice the noise when you are turning at low speeds.
If you have a growl or whine going straight down the
road when you engage 4hi or auto 4hi....you most
likely have front diff bearing problems. Since you
have the heavy duty version, you would have the
large 9.5 inch front diff. On these, we see both
the side bearings and pinion bearings failing. On
the smaller diff, it's always the side bearings. On
the larger front diff, if it's the problem, you will
need to have it overhauled, install an updated
vent (to handle synthetic fluid) if it hasn't been
done yet, and fill it with synthetic fluid.
What do you mean when you say that you
contacted GM? Have you taken it in to a
dealership and had it checked out?
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