Limited Slip or Other Problem?

[cghoerichs]

I tow a lot of weight with my 2002 7.3 F250 4x4. I've noticed this spring that when my gooseneck trailer is loaded with hay it feels like my back tires are grabbing and lurching when I turn sharp, like when you are in 4x4 and try to turn on pavement only this is coming from the rear. I've also noticed that my back tires are waring faster than my front. Going strait there are no rear sounds or unusual issues. Is this symptom normal? I do pull a lot of weight, sometimes as much as 18,500lbs including my trailer. Light loads on the gooseneck don't cause the issue. The other info is that I changed my diff fluid this winter and haven 't carried any serious weight since the change until this hay season and never noticed it before now. I have the 4x4 sticker on the body and have a c1 axle on the door frame so I assume I have limited slip.
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[scagle1]

Did you use the limited slip additive ? Post up what you find cause i'm having the same issues and about to replace the clutches in the rear end to see if that solves it as the additive didnt.

[cghoerichs]

I just added the additive and haven't pulled a heavy load yet. I'll be cutting hay this week if the weather holds. Then I'll know if it works.