Ok so I backed out of my driveway this morning. And m car just locked up and wouldn't go. At first I though I backd into some thing. Felt just like the e brake got slammed on the car just stopped and no matter how much I pushed the pedal it wouldn't move. So I put in drive and pulled off it was ok for a sec then boom. Back tires locked up and skidded to a stop again felt just like when you put the e brake on. Is this my tranny? Torque converter? Differential? Its a 4r70w mild j mod, new filter an fluid (about 400 miles since flush and fill) rear end is 373 done at the best shop in town about 4 years ago gear oil has been changed regularly. Any thoughts? I'm at work and havenot had a chance to dig in and I know there are a ton of tranny masters here. All advice is welcome.