I have an 82 Ram with a 318, and lockup tranny. The right rear brake is hanging. I think it is the e-brake cable doing it.

Is there a way to free up the cable, or is it best to replace it?

 

It would be tough to get some solvent like PB Blaster to work its way all up along and inside that cable...
But before you replace it, you might want to spray some solvent (liquid wrench and wd-40 work real good too) on all moving parts anyhow, let it sit overnight and loosen it all up real good.

That way, if it still doesn't work, at least the parts should move easily when you go to replace it