Is there in fact a tsb re the shudder coming from the rear diff?Only shudders on the first turn then alls well.

 

it sounds like you need to replace clutch pack, but hey its not serious ( just annoying)...just need replace it with better one..
Try search " clutch pack" or shudder.

I have the same issue with my FX4 04.

i m waiting for Ford service dept to call me once the parts are in.

YOMAN!