rear end noise - I'm getting a loud klunk when my truck upshifts from 2-3 at low rpm's and it attracts attention in light traffic. I can also make it ...

I'm getting a loud klunk when my truck upshifts from 2-3 at low rpm's and it attracts attention in light traffic. I can also make it klunk at low rpm's if i downshift manualy from 2-1. The dealer says this is a bulletin from GM saying it's a acceptable problem and should not be fixed per any warranty. That's is Bull _____....
So with the GM technician in the truck i stepped on my brake and shifted from 1st to reverse back and forth and it made a loud klunk every time. So i said, yea that must be my transmission shifting from 2-3 huh?
I suspect either my ring and pinion have to much backlash or the spider gears are worn.
When i got home i checked my unversal joints (perfect) and did a pinion gear run-out (where the yoke is) with my dial indicator and i have .250 backlash.

I'm haveing the exact problem! in the same spot too between 2 and 3, and sometimes into reverse and drive! id dosnt do it all the time but sometimes more than others... i thought i was the only one with this problem!

mine does the same thing i pulled the center section and the spider gears are worn, the bad thing is its a locker and you can't get it apart to replace them like a standard differential. The service manual says you can but my veteran rear end guy says you cant get it apart with out damaging it and even then you cant get the parts.

Hey Rod. We all know things can come apart no disrespect to your tech. The corporate service bulletin says all 2012 and previous transmisions 4l60-e, 4l65-e, 4l70-e, and rpo's m30, m32, and m70
There are plenty of you tube videos showing the disassembly of our locker type differentials.
How much gear backlash did yours have? Mine is .250 at the pinion yoke.