hi, I removed my rear wheel today to get a new tyre fitted, my rear axle does not have a castle nut and cotterpin, I have a GS500e 1993 ...... Did they come out with them or only on later models??

I'm from Aus so i'm not sure whether the US and european models are the same as ours??

At least in the US, newer ones did not have castle nuts and cotter pins. They had those nuts that grip (whatever they are called).
quite possible your axle had been replaced with a newer one at some time.
If the axle has holes for a cotter pin, then someone replaced just the nut.
You will be OK as long as things are tightened down and you use thread lock on the nut.

Mine does not have the castle nuts either. Its normal in Australia.

Sent while taking a dump

Ok, Thanks ...... if thats normal then I guess its all good New tyre going on tomorrow, as the old one was getting a bit scary in the wet. 

No castle nut and cotter-pin.
That's on my "to do" list....at lease it is drilling the axle & putting a split pin there.