The RX55F-FT rotator can be mounted to a flat surface such as a quick coupler adapter.  The bolt size is 12mm.  The hook up to the attachment is a square 4 hole pattern for 5/8" or 16mm bolts.

The top part of a rigid rotator can be mounted to the quick-change adaptor, and the bottom part is bolted to the grapple or other attachment.  The incomming oil fittings are on top.  The out going oil to open and close the grapple are on the bottom and all are JIC fittings

Hook up dimensions are in millimeters