HI all.
Ive noticed an issue with my 02 1500 5.9. When going up severe slopes...ones that are 20% grades or more (Im estimating )
the trans will pop out of gear. I think it is fluid starvation. The fluid level is about right too. It has only done this a few times...
Is that what is going on?
Here is how steep it can get - and this isnt the steepest

 

I would pull the pan and check the condition of the filter and go from there. Try to save the fluid in case you can reuse it.

 

Install a deeper pan and a longer pickup tube.