Hi There, I'm Clayso a certified master automobile technician with 30 years of automotive repair and diagnostic experience.
I've chased moans, groans, squeaks all over General Motors products for years. Since the moan is in the front and changes at different speeds and whether under a load or not, this narrows down the possibilities to the drivetrain. If you can change the moan by steering slightly left to right this indicates wheel bearings, but does not rule out things like several different transmission bearings. The engine itself can transmit noises through the mounts depending on the engines position when the noise occurs. Chevrolet issued a technical service bulletin several years ago concerning a moan from the power steering at highway speeds, the main cause was low power steering fluid.
General Motors and many other manufactures recommend Chassis Ears for determining the cause and sources of drivetrain and really any other noises. Steelman offers chassis ears both wired and wireless. Personally I prefer the wired, there are 6 sensors instead of 4, the sounds transmit better, easier to isolate specific areas, and the headphones really help isolate outside noises. Chassis ears are a small investment, but can save you money in the long run versus simply changing parts and hoping.
I hope this information is helpful. If you have any questions let me know. You can reply back to me through this thread at any time.
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