Hi there, I’m after a ohlins (or Maxton) rear shock for my monster 2004 620. I’m in the middle of converting it to a DD (Desmo Due) race bike. I would also consider a 748/749 unit as I believe they also fit the monster.
Some don’t fit easily, check how the reservoir fits (748 etc). I had an ohlins fit straight in with a wiggle, whereas Norton and Hagen iirc have to be upside down.
Just sent you invite to a FB group on bike spares, you don’t seem to be in the group so can’t tag you, but there is a 916 ohlins shock on there