Hi , I had a local HD dealership change the swingarm on my '01 RKC to a '03 swingarm, check for the newer swingarms at a trike builder, reasonable cost, the '03 looks to be stronger, more steel
After drilling out the rear brake to 1 inch diameter, the modified rear brake did not look strong enough, it was replaced with a newer brake
Some drilling had to be done to the frame to get the newer swingarm to fit, I am not sure why, maybe to use the newer swingarm bushings? I will find out this weekend
Reason for changing was I wanted 1 inch axle for the Weld Racing rims, I can put these on the '01 RKC or the '06 CUSE
Another reason was for a thicker rear axle, I weigh a bunch, during my mountain bike years I bent many rear axles