On my 2009 z71, reverse will kick out and grind/spin sometimes. 88xxx miles, also feels like some tugging up hills. No engine lights.

 

manual or automatic?

 

It is an automatic. With the 5.3. Mostly in reverse.

 

unfortunately , grinding indicates a failed transmission. It has to be replaced.

 

It only happens sometimes when I put in reverse and quickly give it has. If I'm easy on it, it's fine. And there is no other sounds from it. When it kicks out, it's like a higher sound the goes with the rpm. Almost like an electrical grind. Not a real metal to metal grind. If this makes any sense.

 

I hear ya. Unfortunately the answer is most likely still the same.
I assume you did the obvious and checked the transmission dipstick.
You can try taking it to a transmission specialist shop so they can run a diagnostic and check it out for you.
If you're feeling adventurous, you can drop the pan yourself, and see what comes out.

 

Fluid is all good, and clean. But will do some more investigation