Help, leaky 727

I torqued mine to 150" lbs. with no problem. Some silicone sealers don't lend themselves well to ATF. They make special RTV for auto transmissions but you don't need it with the reusable gasket. You install it dry. Every time I've used one it hasn't even as much as seeped. Usually it's something else leaking down making it look like the pan is leaking. I see you say you checked all the other area's prone to leaking but you might want to check again to make sure you didn't miss something. Check the front band adjuster lock nut too. I've had a couple I had to crank down real tight to keep from leaking.