Have you tried Giant Shark for motor spares, motors and esc's?
You are really looking for a 3mm (double check with some of these Vernier Calipers http://www.giantshark.co.uk/digital-...-p-403716.html
) shaft with the correct "C" clip groove and grub screw cut outs. It won't matter if it's too long as you can cut off any excess and you can always use a 3mm wheel collet to retain the shaft if you can't find one with a suitable "C" clip groove http://www.giantshark.co.uk/collets-...-p-406788.html
Here is a selection of 40 amp esc's http://www.giantshark.co.uk/40-amp-esc-c-21_91.html
I'm running one of their 2600kv 36 gram motors on 3s in my Parkjet. Have swapped out the esc from this video but not had chance to run her yet.http://www.giantshark.co.uk/a22088-2...-p-405607.html
And here is an earlier video of the same spec motor in my Flycat