On Saturday my sons and I were cruisin on the highway in stop and go traffic when we notice smoke coming out from under the car. pulled to the side of the road and the car stop moving while in drive. We parked i got out and sae about a quart of teansmission fluid on the ground, It would no longer move in gear. We got towed home about an 1,5 hours later and when it was removed from the flatbed I tried it again and it drove in both reverse and drive. Any thoughts on what maybe wrong and where i should go from here. I thought it maybe the that tranny seal that blew. Not sure where to start

First item to check is the fluid level. Try to determine where the leak is: pan, tailhousing, cooler lines, etc.? This is pretty common on our older 'birds. You may get by easy with just a simple gasket or seal replacement. Let's hope.