I spoke to Barnett about this and they are a mytified as I am. The handle bar controls and the clutches are exactly the same on both of those models so there should be no difference in the cables. The exposed wire length on 87-2006 5 speed applications is 2 3/4". The 06-09 Dyna and 07-09 Softail has a different exposed wire length at 3". Sorry, I can't help here.
As far as tearing up cables, Make sure you are not putting a bind on the cable from an improperly adjusted clutch. The major cause of new cable failure is the clutch ball and ramp not being fully retracted when the new cable is adjusted. The balls get to the top of the travel and the stress goes right into the cable. Also make sure the routing doesn't include any sharp bends, as that could also cause a stress area and potentially break the cable as well.............