Hi, I am John Mc, a Ford dealer technician.I hope I can help solve your problem quickly and accurately.
Sorry but I can't tell what axle ratio you have from your vin. If you could get the axle code off of the door tag I can find the info for you. If you are feeling a shuddering when pulling off and slightly turning you probably have slipping rear end clutches. This is usually easy to fix. Go to a dealer and get some rear end friction modifier. Get two bottles and put it in the rear end and go do some figure eights with the truck to work it in and it usually solves the problem. If not you will need to replace the rear end clutches.
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