I don't think my rig spent its whole life in CA. forget where it was from originally. my hard lines were looking rough and wanted to just avoid it before it corroded out and dumped my coolant. Was easy to just run all soft lines; took maybe an hour at most to do it?
I used 16ft worth of 1/2" heater hose to bypass the hard lines while keeping the rear heater. Didn't want to deal with replacing the hardlines so just ran soft lines on a new route for the whole thing.