Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
It will fit Ian but whether the indicator mounts are for the smaller 500 or for the larger 550s isn't that apparent from the pic. Easier to source the 500 type, the 550 ones can be hard to find. The 500 one doesn't sweep up as much as the 550 one, this I think was due to the seat being slightly longer on the 550 than the 500 and had a small upsweep on the back as well to accommodate the toolkit.