95 mustang gt need help on leak!

Have you or anyone else added transmission fluid to the car recently? There's an overflow valve on top of the tranny, near the back. When the fluid gets warm, it expands and it overfull it can pour out the overflow up top. I had that happen to me, but the smoke happened when I was driving uphill - the fluid level finally got level with the overflow valve, and I made a nice smokescreen until I leveled off.

You could also have a leak in the transmission pan or the rear main seal. The only way you'll find out for sure is to get under the car. Do you have any tools? A floor jack and a pair of jack stands?