I have a 2001 Suburban. Never slipped never skipped a beat. I'm getting into highway and press the gas but feels like I'm in neutral. I have 1st and rev. Drive home and made it rpms never went over 2 1/2. Drive 50 all the way. Turn it off and next day I have nothing. No gears at all. I checked fuses. But not sure if I should just put a new tranny in or not. She's got almost 400,000 miles.

 

If the ATF is topped up then your trans crapped the bed. Probably not worth another one. That money should go towards a replacement vehicle.