engine: OS 25 LA. recommends 9x6, but Im looking for one that Is short.. heres a photo to help explain what I mean.
excuse my crude paint job.

some are really long, and some are short. I have to order them online since I don't have any local RC shops in my area. I use Greathobbies.ca and the site doesn't say how long or short that middle piece is.

I was recommended, from my previous post, to get a aluminum prop nut, because on my plastic spinner my prop nut would sometimes get lose on when I applied the starter. a 10 mm wrench fits the prop nut. I've been looking online and theres a lot of different sizes for these what do these sizes mean? and would this one fit? http://www.greathobbies.com/productinfo/?prod_id=DUB740