I've been figuring out my suspension as well. Seems there's a lot of conflicting info around. When I first went into the dealer their book suggested I had 43mm forks (2002 Adventure R) but I was pretty sure they were 48's. I ended up pulling a spring and giving it to them to measure. It's a 48. I've got it out in the garage so I'll measure it and let you know the dimensions.
When they measured it, they said it was the same spring they are using in the current 950's (not sure whether S or not) so I'm pretty sure if you have the same fork I do you can at least get 48's from KTM. That's probably what I am going with.
Perhaps we need a thread to start collecting this data in one place.