James Get yourself over to H-cafe this evening and tell us what it is your after as sssa doesn't relate to any Ducati I know of Or is it code for Super Sport Swing Arm, can't be as its the wrong section So must be Single Sided Swing Arm Hole in which case its about 26mm, probaly clearance size for a 25mm shaft to go into it, I measured the spindle as it was easier than digging out a paddock stand
cheers mr skidlids! sorry for confusion - i thought sssa was a universal acrnym for a single sided swingarm, so somewhat lazily typed that.....26 mm sounds just about right - will pass on info.