Doesnt seem to make the sound all the time. Mostly does it under load or going up an incline. Its kind of like a clunk and or grinding noise, Kind of hard to decipher. Today while going up an incline it actually stopped and it sounds like something spinning and then it ingauged again and it would move. I checked the clutches and installed a new belt before it did that also. Rear drive shaft seems ok where U joint is too. Has all new rear CV shafts and bearings and al new bushings in rear arms. Also flushed out the rear Diff with no shavings. Any ideas or where to check.