I've seen several of my dirt track racing competitors narrow rear axle tubes and shorten the axles. They usually cut the flange off, bored the center out, and press-fitted the flange onto the shortened axle shaft before MIG welding it on both sides of the flange. Very few of them broke the welds, even under the stress of repeated high RPM full throttle applications and rough track surfaces.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!