Rear drums??

i recently bought a 51 plymouth cambridge, how the hell do i get the rear drums off?? it has a large castle nut on like a spindle i took it off but the drum wont come off, is there more i have to do? i see theres like a square piece on the drum or something thats only on one part of the inner area not sure what it is, but all i took off was the castle nut, anyone help??

 

alright nevermind i see on a website i have to use a special rear brake drum puller for these

 

el6nino9 - I sent you a PM