how hard is it to replace the heater core on a 1985 dodge d350 with ac..

so if the truck used to have air but no longer does and wont, is it the same time.... is it pretty easy to get to ??? is it the same heater core or can you use the one that is actually for truck without factory air.. thanks, jimmy

don't know difference in heater cores. case still has to come out to replace, just don't have to bother with a/c.