if you were driving them both from 0 you could just put d8*-1.475609756 into the drive inner parameter which is the ratio of the distance drive centre (d8) I added a a workplane to achieve this
drive, DRIVE CENTRE NEW, in part SLIDE CENTRE, then look at the parameters to see whats gone on
oh yeah, i just played with this, there may be a better way to do it
Stephen Gibson