Is there a reason for this???????

sounds like the transmission has to be gone through. ask the family to see if they know the answer???

maybe the transmission cooler is leaking and that's why the tranny is grinding. have an oil sample analysis done.

 

is it more of a clicking sound if so a tooth or more are sheared off one of the counter gears.

 

Check your airbags / ride height, make sure it's correct.

 

I just visited a buddy of mine that works at Freightliner, he was showing me a pile of transmissions that had come in over the last few weeks. All of them had failed due to transmission cooler / cooler line problems. One of the trucks was a 2013 with only 1200 miles. I would see what it takes to get that cooler hooked up before you start damaging that transmission. Get an oil sample done to see how much damage there already is.

 

i saw one of those over at roehl. the cooler failed AND the trans temp gauge at the same time. engagement splines all chewed to bits. that would make a noise during shifting, i think, but noise during normal operation would seem to be a bearing.

 

You might also check the drive line slip yokes for being free to float in and out. When they get froze up they'll cause trans/diff noise and take out bearings.