Daler442

It was in 4wd already, had been for 30 to 40 minutes. Wasn't horsing it. I let it shift to drive, was taking it easy. Just don't get it

New to the site, have a 2021 2500hd with 6.6 gas. Yesterday was turning around in my driveway and heard a bang, then check engine light, trac light, reduced engine power, service parking brake lights all came on. I can run through the gear shift, but it won't engage any gears. When I have it in r or d if I touch the gas it revs up and speedo keeps going up. Looked at shift linkage and it does move, so I'm guessing a serious internal trans issue?? Anyone else have an issue like this? Thank you , Update, just pulled code p215b , output shaft speed correlation