Tonio, I've just had a look... and contrary to my earlier comment, my monster spindle is the same as my 996, which also looks the same as your sport.

2 different spindle sizes for the 620's/600's - determined by age of bike (and on the crossover point, what bins the factory were using:o ) Its like the std marzocchi or showa forks for them too.....
Large ones on the 620's - and very late 600's - and smaller one for the early bikes, as far as & know.......

Thanks all :)