VW coolant hoses (as with most hoses specific to a car make) have
premolded bends in them to fit the hose to just the right places in the
car, and not cause a crimp in the hose (which among other things can
mean reduced coolant flow and/or premature failure of the hose.)

However, I found certain of those hoses are just about impossible to
find for our Vanagons now a days, and generic, non-pre-molded hose
needs to be used in its place.

Since this is for your heater core, its not as critical as it would be
for or around the engine or radiator. Still, just be careful how you
run the generic hose (if you choose to use that) so as to not put a
kink in it.