From what I and other Techs around the world have found from changing the 8V clutches & 2V CARC clutches is that you never need one. I used the tool on my 1st three, None needed. This is why you will not find any for sale and they discontinued the part numbers.
No one ever ordered any, ever. I've changed around 7 8V clutches and all been good.
I do believe Guzzi was worried about quality control on the thickness of parts assembled, rod wear and such.
If you need to measure yours do as John says or you could seek out a Guzzi dealer that has the tool & buy it from them.
There are no rods for sale at any importer in the world, I have checked.