Ben, Have contacted McGraths and they have examples of the clutch cylinder, so don't need mine as a pattern. I'm sure they will sort you out something. I need the dimension of the max mark from where the dipstick contacts the top of the tube in the dry sump tank. I doubt that the overall length is consistent. The two measurements that are taken the same way on the dipsticks I have as your 166, are 140 and 200 ! Maybe it's not that critical Neil.