Loud clunking noise

[CRIMSON GMC]

This is my first post on this form. I have been reading for a while and have learned a lot of great info. Now I need some help.

 

First of all, let me apologize for shamelessly steeling the picture from the grease zerk guide. But they say a picture is worth 1000 words.

 

My 01 Sierra is making a loud clunking noise when I accelerate in 4wd. The dealer thinks it is the axle flange hitting against the draglink (I think that is what it is called, the flange by the number 8 in the picture).

 

I can see that this has been happening because there is not enough clearance between that flange and the drag link. The dealer’s solution is to replace all of the parts. I would like to find that part that is causing the problem and only replace that.

 

One of the theories the dealer has is that the idler arm has been replaced with the wrong part (I bought the truck used). They were not able to figure out what part should be on the truck (so of course they were going to replace it to be sure).

 

Does anybody know the correct casting number for the idler arm on a 2001 2500HD CC 6.0L.

 

Are there any other ideas? I am also thinking a bent drag link. It looks like there is a little bit of a kink, but I don't know if it is supposed to be there (once again, dealers solution is to replace it all).