Most people seem to just go to 31 spline stuff while they're at it. The axles cost the same and then another $100 or so for a used 31 spline T-lock and $80 or so for a good rebuild kit with the good clutches. The only time I've seen anyone just do the aftermarket 28 splines was a couple years ago on the Mach 1 Registry. A couple guys did it and one or two of them broke one on sticky tires. It's your call.