Best thing to check would be at a dealer. Otherwise you could try to piece it together from what a newer unit has in it for parts and buy it separately. The air conditioner will be the tough part, as there are a lot of components that go with that.
If you are just looking for a heater, there are some good aftermarket kits out there. Inferno probably being one of the best, the bypass valve is also helpful for heat in the extreme cold.
Steve