Shuddering from rear, 20 TRD OR

Evening all,

Recently got my differential fluid changed at the dealership. Went to the beach today and had an issue.

While in 2wd, hit the sand and as I increased the rpm against the drag, the rear and of the truck started shuddering up and down rapidly. Usually it would start to bog down as it hit the traction issue and when it would get uncomfortable, I'd kick it into 4wd.

After the shudder, I put it in 4wd and still had a pretty severe shudder from the rear. I put it in 4lo and normally it would plow through sand without issue. It needed a ton of throttle to get it to move even a little. Finally I put it in crawl control and it wouldn't even move despite turned up to max speed.

I ultimately went back to 4hi and shuddered my ass out of the sand and back onto the gravel.

Did the dealership screw up my differential?

 

Very well could be. I've got a fair amount of time on the sand with beach camping and fishing, never felt this shudder. I didn't air down so that may very well be it.