Nikon Eclipse Ti2 epi-illumination port clear aperture

Hi all,

Would anyone be able to tell me the clear aperture (a.k.a. minimum diameter) of the epi-illumination pathway on a Nikon Eclipse Ti2?

I estimate from the blue prints in their brochure that it is between 36 and 43 mm, but it would be nice if someone with access to one of these scopes could confirm this. Links to the full blueprints would also be welcome.