Classic/Antique Car Repair: 65 Cad/Differential, rear tires, brake shoes

Question
I have a 65 Deville that may need diffentials from towing years ago as the rear tires are stuck? I am not a mechanic but was told it was the differntials. The brake pedal is hard and the car has been sitting for more than a decade. How can I get the rear rolling for towing until able to figure out what could be the problem??

Answer
this is out side my expertise as i primarily focus on the English makes. first i would remove the rear brake shoes perhaps they may be seized it will far less of a project than the Diff. and it is something that may need to be done anyway in order to dismantle the Diff assembly.I hope this helps