Thanks for all the info guys, this is what I needed. With this info I can see if a "typical" F18 Spin will fit or if I need a custom spin.

I now have to measure mine and see if the average 8.5m luff is more or less than what I have. I'm hoping mine is 9m. I'm sure it's not but if it is, I have a solution. And it opens up the market for used F18 spinns for me.

Thanks again