I believe your parking brake is located on the back of the transmission shaft. It will be a standard Drum Brake with a mechanical linkage.
It is about as simple a job as there is. If the linkage is intact you need to replace the Brake shoes. They may be an a oddball size but they can be relined.
There used to be a place across the street from the back lot of Marshall Mize Ford that relined brake shoes. Car Parts Inc in Cleveland can get them relined for you.
I assume the linkage had been adjusted to take out all the slack??
Truck dealers can do the job for you. You Probably have a Chevy C-30 frame.
