Please advise,
I need to mod. Ohlins rear shock from 1098 fit to Monster 1100, it possible or not.

Thank you,
Wirun

Nope.  If I could'a, I would'a.  Being as my bike is not a track machine I am happy with the 737 I ended up with.  There was a vague promise of being able to upgrade it at a later time.

The reservoir on the shock in your hand will not fit under the tail.

the only SBK rear shock that *might* work on the 796/1100 is the Ohlins from the 749S/999S.  I took some measurements of it a while back and the eye-to-eye and reservoir layout were doable - but no way to tell for sure until its actually mounted up.  You would of course need to have it revavled and tuned for the monster though.