This unit came out of my 69 Torino and is in really nice shape. I believe it would fit a 66-69 but double check on the 66-67 models.
The heater never leaked but I would still replace the core as it has sat a long time.
I would bet this is somewhat hard to find especially in this kind of shape.
Before I put it on fleabay, Someone who really needs this contact me an make a fair offer.