How do you change a heater core in a 1981 Granada?

The best way is to do it the same as I did, cuss, moan, groan, take a mus. relaxer & pay someone else. But truthfully if you havw the time find where the 2 hoses go into the firewall for the coil & go from there it`s not easy & it`s very time consuming maybe even two days worth of work & a lot of tools but you can do it.