The left rear wheel bearings SUCK in the old rancher 350's... a trend that continues even today. The Axle tube seal doesn't work particularly well, that bearing is always the first to go out. Problem is, once that bearing is gone, it puts excessive strain on the axle splines in the rear end and it will strip out the splines from the ring gear and the axle. I don't think I've ever bought a honda that the left rear bearing was still there... The right side is always fine because there's 2 large wheel bearings in the brake assembly (though those drums are always full of nastyness I can't even begin to describe... Funny how well that seal holds the stuff in there, but obviously not very good at keeping it out!
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If you're looking for IRS, I'd try and find an older Polaris Sportsman. They're very stout, driven by a drive shaft, and those older sportsmans are pretty cheap, especially if they're really ugly and/or have motor problems (and almost all of them had problems with the exhaust lobe on the cam shaft... but don't get me started there!
Cheap bike and easy fix...) But the rear ends in them, seldom ever have problems and hold up to a lot of abuse.
I believe the sportsmans started in the mid 90's and have always had IRS all the way up to current models.