Not 100% sure, but do you want something like:
http://www2.towerhobbies.com/cgi-bin...?&I=LXD827&P=0
These go on to the stub of the strut, and provide the axle for the wheel.
Check your instructions.
gus
P.S. This is a better link...
http://www.shopatron.com/product/pro...0.70.121.0.0.0