I have an2003 F-250 with 130k miles. I never had the Dealer recommended REAR END SERVICE preformed. Know after torubleshooting a noise to be the Mid-Shaft bearing, I noticed while on the hoist both rear tires spinning. After looking further it acts like rear end is locked in. I hold one tire and have the other try to be spun. Both tires spin same direction. The same happens spinning the driveshaft. would an additive help or is a tear down and inspect the only answer. This is really killing my fuel mileage and tires. HELP!!!!!!

 

isnt this normal? i have ls and both my tires rotate the same direction while on stands..
i think im missing the question. but im sure this is normal operation.

 

The stock LS uses friction clutches, so both tires will turn the same direction until a torque difference is reached, then the clutches will slip. What you describe sounds normal. Now if yours never slip, even when turning sharply (like in a parking lot) then your LS could be damaged and bound up.

 

^^^ to add to that you will know by it screeching or dragging while turning

 

I have an '02 with roughly the same mileage, and I may have the same problem as you. Both rear wheels turn together....90% the time.

Dirt roads, inside rips up everything. Turning on paved roads, from a dead stop the truck shakes (probably from rubber getting good traction), but while rolling I don't feel anything. Then again while rolling I don't take 90deg turns.

I'm due for an oil change on the diffs, but I'm worried of what I may find when I crack the case......

I'm not sure what type diff I have (5.4L 4x4 '02), but the mention of clutches sounds like it could be a culprit.

Any idea's on repair costs???

 

Like what was said b4, that is normal unless it never slips on pavement causing severe scrubbing/or a loud clunk chatter. Additive for the limited slip might help since thats what its for, but u also could have a bad limited slip. If it was mine i would be happy, I dont want slip unless its ruining your tires. I would change out the oil and additive first then see what happens. Rear end stuff isnt cheap.