big let down car will not move now

Was all set to take car out for a short drive down the street [for the 1st time] on Thursday before Christmas, just installed 17 wheel tire comb. made sure has clearance all the way around on all 4 wheels. got in car fired up engine let it run for a few minutes to the engine come up to temp. put car into reverse [auto trans. 904]to back out of the garage, could feel the trans. go into gear , gave the car some gas to back out and the car would not move, thought ok did I forget to release the parking brake, checked and it was off, tried again put into reverse still would not move gave it some more gas still would not moved then put into drive o see if the car would go forward in to gear gave it some gas and the car move a very little amount then just stopped, the best I could get was to rock the car forward and rearward. was able to jack up car and back off some more on the parking brake cable just in case it was not fully released [ have moved car in and out of garage at least 10 times before with no problem till now], still would not move, this is a 69 cuda has front brake disc, none factory aftermarket kit[the right stuff detailing package], drum rear brakes, all brake parts from front to rear are new, ran out of time to look more into the problem, I will jack front of car up soon to see if the front wheels turn I think at this time it may be some thing to do with the rear brakes locked up, the brake pedal seemed to work/feel like normal any thoughts ??