There is a TSB about drive shaft noise. It is a harmonic vibration that they fix by replacing the drive shaft with one that has an extra vibration damper. Sort of like the harmonic balancer on the engine.
TSB
07-20-7 MOAN/DRONE AT 1500-2000 RPM - DANA 80 DUAL REAR WHEEL AXLE
Publication Date: September 24, 2007
FORD: 2008 F-Super Duty
ISSUE:
Some 2008 F-Super Duty 350 Chassis Cab vehicles equipped with a 6.4L engine and a Dana 80 dual rear wheel (DRW) axle may exhibit a 4th order engine moan/drone concern between 1500-2000 RPM.
ACTION:
Follow the Service Procedure steps to correct the condition.
SERVICE PROCEDURE
Replace the driveshaft with a revised part number per application. Refer to the 2008 Super Duty 250-550 Workshop Manual, Section 205-01, for driveshaft removal and installation procedures.
PART NUMBER PART NAME
8C3Z-4R602-EEA Driveshaft Asy - 140.8" WB/4X2/AUTO/DRW
8C3Z-4602-AHA Driveshaft Asy - 140.8" WB/4X4/AUTO/DRW
8C3Z-4R602-ADA Driveshaft Asy - 161.8" WB/4X2/AUTO/DRW
8C3Z-4R602-BMA Driveshaft Asy - 161.8" WB/4X4/AUTO/DRW
8C3Z-4R602-AMA Driveshaft Asy - 164.8" WB/4X2/AUTO/DRW
8C3Z-4R602-AVA Driveshaft Asy - 164.8" WB/4X4/AUTO/DRW
8C3Z-4R602-AFA Driveshaft Asy - 176.2" WB/4X2/AUTO/DRW
8C3Z-4R602-BDA Driveshaft Asy - 176.2" WB/4X4/AUTO/DRW
WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
IMPORTANT: Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.
OPERATION DESCRIPTION TIME
072007A 2008 F-Super Duty F350 6.4L Chassis Cab DRW Axle Dana 80: Replace The Rear Driveshaft Includes Time For Diagnosis And Road Test (Do Not Use With 1007D, 1007D7) 1.2 Hrs.
DEALER CODING
BASIC PART NO. CONDITION CODE
4602 D9