That type of AC was normal on pre-86 water cooled vanagons. It was a
factory option. Based on the age of it, you're probably better off
getting an AC shop to make all new hoses for it anyway (including the
front one). One problem with this AC unit is that the plastic used
tends to be somewhat brittle in the present day. On the passenger side
it is held up by the curved section of the sliding door track (so if
this is going in a doublecab, a custom bracket has to be made.). On the
drivers side, the hoses from the evaporator are hidden behind a couple
of plastic pieces right behind the driver seat (which means if you have
a westy stove in that location, you need to route the hoses carefully.
You also will need to put a hole in the wheel well for the hoses to go
through (make sure you use a rubber grommet to seal the hole as well as
to protect the hoses.