My flex shaft size (wire part) is about .150 size and the prop shaft size is 3/16 for the strut and then 1/8 for the prop.(just realized I measured it wrong.[:@]
I guess I could get one of those octura hardware sets that'll have the right sized shaft, but I am on a bit of a budget.
http://www.offshoreelectrics.com/products.php?cat=69