I needed to get some assistance for my XF100-400mm, and I found this SevenOak
CF Gimbal Head Adapter. It functions in much the same way as the Wimberly
Sidekick at about $100 less costly. It attaches to my ballhead tripod mount,
and works perfectly.

https://www.dropbox.com/s/kqj6mqszmxy3bhn/IMG_2577e.jpg?dl=0

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Regards,
Savageduck