I think the FXR4's had 12''. The real point is the bushings are common between 197? to 2003 Sportsters and FXR's so they bolt right on. Not sure what the oldest Sporty shock works, but I ran a set from a '79 Sporty for a few years.
2009 Suzuki V Strom 650
November 2016 V-Twin Forum Ride of the Month