I am having the same problem on my 05 screw 42,000 miles.It started on a 1200 mile trip to colorado.started about 200miles from denver.I changed the fluid to royal purple which already has the friction modifier in it because my old fluid looked like motor oil it was so dark.still does it .I drove back to michigan another 1200 miles and still doing it so I got a Ford clutch replacement kit off ebay for $25 plus $13 shipping so I will be changing them this weekend and see if it helps.Its real annoying.

 

You know, I had the shudder on my 04 FX4, and change all the fluids/etc.. but the front diff. Changed the front diff last week, and amazingly no shudder? Not sure why. I do know that the front diff fluid was DISGUSTING and VERY dirty. Who knows. I would suggest it just to cross it off your list.

nolo

 

Well the new ford replacement clutchs came and they are different material then the stocker had.The old ones are a solid piece of clutch like one found in a dirtbike or atv and the new one is carbon fiber(suppose to be better) and has 3 sections on each side so completely different material.Let everyone know ho it works tommarrow when i get it back together.

 

How did this work out? I have an '03 HD with 22k miles, same problem. The Ls and HDs have the 4x4 9.75 diff.

 

Well the shudder is gone and they seem to grip just as good as the others did.Only problem with doing it myself was it is super hard almost impossible to get the stock spider gears and thrust washers back in the stock limted slip.Everything is super tight with the new clutchs and cupped washers that go behind them making it really hard to get the spiders in since you have to compress both sidegears which have the clutchs behind them.Ford quoted me $800 to do the job and I did it myself with Ford parts off ebay and RP oil for $55 so it saved me money I didn't have.If you have the money take it in if not take the carrier out yourself and buy the parts yourself off ebay and take it in to Ford and have them assemble the carrier and then put it back in yourself.Might cost you a $100 to have them rebuild you carrier but still a lot cheaper then the $800 tyhey quoted me to do the whole job.