Just bought a 03 gmc 3500 dually with 50k on it. Had iT for about 5 weeks no issues. I went to put it in drive yesterday and the indicators didn't light up for drive, neutral, and second gear. Then, BANG!! It shifted into drive. Then I did it again to make sure. BANG! Now I'm getting hott. So once I leave the mall, I step on it. There's a lil hesitation in second gear. Its not too bad. But today when I went to go to work, I got a BANG when I put it into drive, then I was going down the road and it was reving really high without shifting. I put it in 3rd and back into drive and then it shifted and the indicator went back on. Then shut off shortly after. Any ideas? Dealers taking it in on monday but I don't want some bullshit story from them. Thanks appreciate it.