Transmission shifting poorly in lower gears

poor shifting especially downshifting in lower gears
Checked transmission on DAD. No error
Checked transmission data stream unusual RPM wheel 2 ( 410) RPM wheel 3 (0 )This is while standing still Does this indicate faulty wheel sensor?
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2006 2500 118wb cargo 104,000 miles

The transmission has it's own internal speed sensors. Doktor A discusses cleaning them here:

https://sprinter-source.com/forums/forumdisplay.php?f=104

I found my shifting problem. Instead of going to the transmission I thought I'd start
at the differential. https://sprinter-source.com/forums/showthread.php?p=189909#post189909
I couldn't believe that the differential oil could affect my shifting so severely.
She shifts as smooth as goose s**t on glass now Just changing the oil
With just 30,000 miles since freightliner changed it, or they said they did, should I change it every 30.000 miles or 20,000? Could something else cause the oil to deteriorate so quickly?
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2006 2500 118wb cargo 105,000 miles

Most people go a lot longer before changing the fluid in the rear end. I suspect that it may not have been changed (or something completely wrong was put in at the last change).