Slip yolk squeak

Hope someone has heard of this:
I have a 2013 raptor 56778 miles, I went off-roading in a lot mud. When there is no load on the drive shaft and you accelerate there is a squeak noise. I did take this to dealer. They dropped drive shaft found mud in the spines of the slip yolk cleaned and greased problem gone. About two weeks later squeak came back went to dealer dropped drive shaft again said there was still mud in spines greased problem gone, about 7 days later squeaking started again. I asked the dealer both times about the seals and they all tested good. Never had an issue that this dealer couldn't fix usually the 1st time around. Anybody ever experience this any help would be greatly appreciated !

So are you going mudding before each instance? If not, how does mud keep getting in there?

@Yukon Joe
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No more mudding just that one time, I cleaned and the dealer thought it was not cleaned enough that's why squeak came back. I then cleaned everything front to back it is completely clean and now it came back again. I have more questions than answers I though maybe bad seal, dealer checked and said it was good. Like you said how is it getting in there?

It probably has nothing to do with any mud. Search the Clunk thread here and you'll discover what you have is a common problem.

A lot of clunking going on over the years, looks like some drive shaft replacement. I will bring this info to the dealer. If anyone else has anything I will take that also. Main goal to correct problem for good. Thank you for the help!

If you are getting mud inside the yoke, your transfer case fluid is contaminated also.
Have them drain, flush and refill.

Check the yoke coming out of the front of transfer case for seal damage.
And check the vent tube, it may have disconnected or is cracked.

Thanks MTF dealer will be looking at it tomorrow. Thanks for the input anyone else have anything I will take it might just help, Will let you know what they find.

Sounds like the problem is you have eggs in it...
yolk = part of an egg
yoke = part of a driveshaft.

: )