How hard is it to change the right hand emergency brake cable in a 1982 2WD King Cab?

Not hard at all. Jack the car up and put a jack stand under it so you can safely slid under it. Remove the right tire and then remove the brake drum. You may need to do a little work to get this off depending on its condition. Then once inside the brake area you can locate the cable connector. It is a simple slip on type of connector and you don't need to remove all the parts to get to it. A long needle nose is helpful tho. Slide under the car and find the cable and follow it to the connector from the emergency brake handle. Remove the nuts that secure the cable in place. Then go back to the right brake drum remove the cable. It is pressed into place and might require a little pounding to get out. Look at the new one and you will get an idea of how it is held in place. Once out clean up that area for the new cable and install from the drum to the connector. Then reinstall the drum and adjust both the drum brakes and the cable. This typically took me about an hour and a half to complete with all the adjustments.