There may be a 2mm difference, I couldn't inspect them that closely, I was expecting a more noticeable difference. Maybe I will have to buy a couple of shafts so I can strip them and check them out, its not the sort of thing you can do in the breakers. I'll have to find out if we get the newer Jap models or not - that may be the difference. I know Wildgoody says he has larger shafts from a lwb. The 2ltr V4 swb wasn't sold over here but we did get a lwb version, I looked at the shafts off one of those.