It is one belt and it is 935 mm or 36.5 inches long. They will sell you it as 36.5 incher I believe. Sometimes they are idiots and they can't tell you how long it is - they can only look it up by make and model of the car. Fortunately most of the belts have a part number that is basically the size in inches. I believe mine was like a K365 (36.5 inches) for example.
I have an 85 n/a and I did the swap about 2 months ago. If you run into any problems or have any questions please feel free to contact me directly at the email address in my profile. I ran into every problem that could be thrown at me so I should have some answers for your questions.
The swap works great!!! It is totally worth your time, funds, and effort if you are running a kickin stero system or electric fans/waterpump. I would recommend it highly.