Just replaced the rear disk and pads on my 1999 GTR1000 (Yes I am in the UK) I noticed the rubber cover for the rear wheel spindle nut is badly perished to the point of having a hole in the middle. A simple matter of ordering a new one I thought. I can't find any reference to this part let alone a picture, does anyone know what the Kawasaki part number is or where the hell I could buy this part?

What rubber cover on a spindle nut?? Load a pic of yours. Have you called or taken the old part to your local kawa dealer?

I'm confused on this part description also.. are you describing some rubber cover, that is "over" the rear axle nut, on the right side of the bike?, That part does not exist on any US model ever produced, and was likely "if as I described it" someone's "add on".. not needed.(and may actually hold water in there, to rust stuff up..)... just lightly grease the threads, and the nut, wipe off any excess grease, and insert the cotter key, and lock it..

Note: this is this fellow's first post.

Note: this is this fellow's first post.

I see that, everyone has a "first post", and nothing to be ashamed of.. we are here to answer the questions, and assist..   

It might just be a British thing. They are different like that.

Hi Mike and welcome to the forum. 
To my knowledge the GTR never had such a cover, so yours must be an aftermarket part.
Can you share a picture of it?

It might just be a British thing. They are different like that.

Are they now?

Not sure if it'd fit over the split-pin but will fit over the nut (27mm Across Flats).
https://www.carbuilder.com/uk/nut-cover-27mm-single-black?gclid=CjwKCAjw5Ij2BRBdEiwA0Frc9T0w2UnUFS5Nc_RFKjBZO0rBefqlnja7y1yl60jRiN-oRqRrdyrVpBoCXOUQAvD_BwE
Won't fit on mine as I use an R-spring clip instead of the split-pin.