Just took my truck out for a spin... still have the clunk in 4wd. I noticed I have some play in the driveshaft that seems to be in the slip-joint part of it.

I assume there is splines in there, so could they be worn? I figure when I put it in 4wd and accelerate the transfer case side turns and takes up the play in it and then the front diff section grabs and that's what I'm hearing. I also noticed when I brake with the truck in 4x4 I hear the same type of sound, only quieter. I'm thinking this could be the opposite when the front wheels are slowing the slack gets taken up in the other direction. Does this make sense?

I suppose I could just take the shaft out and look... but it's snowing and damn cold outside and I don't want to move 4 cars to get it into the garage!

 

remove the driveshaft, mark the two halves, take it apart and install the ford slip yoke repair kit grease in it. there is a TSB for this clunk

 

Sorry, I should have mentioned I have a shortened XJ driveshaft.

 

oh your front driveshaft...sorry...it should have a grease fitting int he slip yoke

 

Oops I guess I should have mentioned that too. lol

But yes, I have greased it.

 

if the play is front he slip joint splines the slip joint will need to be replaced, my girlfriends XJ had this problem

 

Figured that's what it must be. Do you think that's what I'm hearing when I'm in 4wd?

 

could be. put the truck in 4x4 and see how far you can turn the front driveshaft with the front wheels off the ground, this will tell you how much play is in the tcase chain

 

Okay, I'll check that out. Thanks!