The 99+ models with rack & pinion steering are 4" wider, so can not be easily fitted to older Kickers. Also the tapered fitting that connects to the wheel hub is much smaller than the older connections. The threaded adjustments are out at the ends of the shafts, so you can't just thread on larger ends. It looks like MAYBE if you tore it down you could machine the threads further up the shafts (making it shorter) with larger threads for the older ends. MAYBE
Not that I have thought about it