axle length problems with side mount stop light.

we bobbed the rear end and shortened the seat on a '78 Kawasaki 650SR. we relocated the stop light/lic. plate bracket on the axle after hackin' the mufflers off. Now the axle nut will barely thread on the axle. Anyone who has run into the same problem and solved it, we would appreciate a response. Do we buy a longer axle? If so, where? We have searched various catalogs but all they offer are stock items. Any ideas would be helpful solving this small problem. thanks
phantom88

make a longer axle;)

Since it is just a longer axle You need ,, Might start by getting its Diameter then how long it is ,Then you might go to a junk yard and start measuring other brands of bikes till you find a longer axle the same diameter ,,

The Unitrac GPz750 axle is a bit longer because of the aluminum eccentric adjusters, but sorry, I can't remember the diameter. The Unitrac GPz1100 axle is too large at 20mm.