I'm in need of some advise. Transmission issue with my 2008 Silverado 1500 4X4. 5.3L last week I was towing a small single axle camper weighing about 2800lbs. I was coing up to a stop sign when I felt a loud clunk. When I pulled over and put the truck in park it started making a clunking noise with a squeezing grinding noise, like two gears grinding on each other.

I shut the truck off, checked the fluid, good color and no burnt smell. Temp gauge was around 180-185.

So I started the truck again and cycled through the gears, the grinding was the same in P, R,N,D..ect

Truck still drives, still shifts smoothly but has very low torque in both drive and reverse.

after a couple hour of driving, grinding and squeezing noise went away. But still has low torque in all gears.

And help on what it could be would be appreciated.