I used a straight edge to align the 3 pulleys. I had to make minor adjustments to the alternator to get it aligned.
I have used a belt that fit correctly in the pulleys which is fine around town but not at the strip. I used a belt that stuck up out of the pulley which I know is not correct. That one didn't work.
The only one that stays on at the strip is the skinny one. It sits way down in the pulleys but isn't really right either.
Sorry, I don't have any better pics on my computer to post and I don't have the belt dimensions available. I bought so many different sizes I don't remember which is which.