I have a '09 GMC Sierra 5.3 rwd it has just under 80k miles. I was driving home and my truck felt like transmission wasnt accelerating pulled over and shut it off. Looking around trans fluid was all underneath the rear of my truck and some on my tailgate. So i dumped a gal of trans but it won't move. Shifting from park to neutral and giving it some gas still feels like it's in drive. But won't move. Took driveline off but idk what I'm looking for.