I have heard about the torque converter sound thing, but I have a customer that has an F-350 that has always sounded like that, and a shop told him it was a bad torque convertor, but it has never had a issue. As lots of my customers have PSD's, I have found some sound like crap, nad some sound good all striaght from the factory.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual