Clock swap

[sinto607276]

mine is a ,98. Not had an issue with the sprocket nut but have not had the cover off so don't know if it is the modified type or not.

Mileage is 38,200

Doggy

You don't need to take the cover off, looking from the rear tyre with a torch, you'll see if there's any thread on the shaft, old nut or if there's no thread, new nut.
But that could also throw in the question of "is the nut slack?" so the best way really is to take the cover off.
But, as been said before '98's seem to be ok but like anything, you have to be clear in your own mind whether you change it or not, as it's your bike and you that's riding it :-)
See here
http://foc-u.co.uk/index.php/topic,17632.0.html
for more info  on the subject