The axle tubes are pressed AND welded into the center housing! I've swapped a tube on a motorhome rear end that was not available anywhere, and it's a real hassle. You'll be better off modifying the spring perches. You'd need to do a complete teardown on the rear end, drill/grind the welds out, push the tubes out of both housings, and reinstall them precisely in the right position, then reweld everything. I wouldn't do it again for twice what I got paid the last time!
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!