Leica lenses are for people who have M mount / LTM cameras. In some cases Nikkor lenses ARE equal or better (show me a Leica lens longer than 135mm that can be used on an M mount camera with accurate framing and focusing and I'll eat my shoe)
Chris, Chris, Chris,
What size shoe and do you want pickles with that??
Technically they don't go directly on the body.
But remember the Visoflex lenses? From 65 all the way to 560mm and do give accurate focus and framing.