I have a 97 GT phase 2 supercharged and intercooled, tranny (automatic) has up to this point been left stock due to financial reasons, well the other day i noticed smoke coming out from my undercarrige which lead me to the giant puddle of tranny fluid I was leaking. Brought it to AAMCO transmissions and all they've come up with so far is that the rear seal blew off due to too much pressure, however they also found that my drive shaft was unbalanced and that is currently being corrected. Any other ideas as to what would create this problem. Sopposedly the stock tranny is built to handle up to 600 HP and right now Im running about 530 to the wheels and 15 pounds of boost. I'd apprechiate any input you all could give.

 

Your vent may have been plugged, I've seen it happen on rear ends (watch out when you remove the check plug) And I doubt that tranny will hold 600 HP from the factory. Why would Ford make a tranny that strong when they can make one that will hold 300 HP for a fraction of the cost. Plus you've now seen living proof that your tranny won't hold that much horse... cause she's a blown!