I wonder if this oil hose routing and the support strap (circled) has contributed to the leak you have. Its a very unusual way of doing it, as normally it goes forward from the motor then turns up and over the trans and then back to the tank.
A replacement hose is available from our host. It is PN 901.107.331.12 and is $107 US. But before replacing it I would do whatever it takes to route the hose properly, even if it means a replacement heat exchanger. Cannot tell from the photo. Do you have any heat at all on the drivers side?
Len