Need help with Tranny and Rear end.

I have a 76 Duster 225(.30 over), 904, and 9 1/4 rearend.

The motor has less than 100 miles on it.
I have a major tranny leak, it is a 904, has its own cooler connected to the radiator. I was not aware of this when I took it driving tonight, the car simply would not shift, with an average speed of 25 mph. Is this typical if the tranny is out of fluid?
I am thinking the seals are bad, Input would be appriciated.

As for the rear end, I believe it is a 9 1/4, when I apply the brakes I hear a loud rattling noise, I am not sure if it is the drive shaft, the drive train or the exhaust shaking around.