What belt do I need?

08 with 2.6 upper pulley, aux idler, and a 15% lower. I'm hoping someone else is running this and can help me out. I have a Gates K100852HD that I was told would work but its to short. I'm leaning toward the K100860HD or K100864HD.

I have my fingers crossed someone can help before I guess......

85.2". Same as my prior setup.

Should be the 85.2. I have a 2.6 upper, aux idler, 90mm idler, ford racing tensioner and 10% lower and run the 85.2. It is a really tight fit getting it on, but it goes.

85.2 was to small. I had the tenchener maxed and still could not get the belt on. It was way to small. I ended up going with K100864HD and it fits perfict.

Thanks for the input, I'm not sure if prior owner has changed one of the idler pulleys with a bigger one or what.