The allen screw and locknut is just what it says, an allen screw and locknut. You just have to figure out what size screw and nut you need and you will be able to buy screws from any hobby shop. My 1/8 buggy uses 3x25 mm screws and these
http://www3.towerhobbies.com/cgi-bin...531+&search=Go .
Sounds like you already have the bushings so you only need the scews and locknuts.
3mm locknuts
http://www3.towerhobbies.com/cgi-bin...?&I=LXFUR3&P=7
screws
http://www3.towerhobbies.com/cgi-bin...?&I=LXWJG3&P=7
or
http://www3.towerhobbies.com/cgi-bin...?&I=LXPJB2&P=7