4 Wheel Drive/SUVs: clunking noise, slip yoke, ford excursion

Question
I have a 2004 ford excursion 4x4 6.0 dsl. my problem is sometimes [85% of the time] when i back up then go forward i here a clunking. i already checked u-joints, and rearend lash. what else could it be.

Answer
Roy,

This could be a loose suspension or transmission/transfer case component, a broken or bad motor/transmission mount.  I have seen this problem with the slip yoke in the drive line hanging up due to lack of lubrication, therefore binding.  This is common in some vehicles.  I would suggest that you have someone stand outside of the Ford, and see if they can pinpoint where the noise is coming from when you go back and forth.

Carl