If using the standard Clio crown wheel an adaptor needs to be purchased and welded to it, most gearbox companies remove the standard diff and post both the new Gripper, the original diff and if the have already purchased it the adaptor, back to Dave Mac/Gripper Diffs, getting the crown wheel removed, adaptor welded and then posted back to who every is doing the job.
Same sort of thing with the Quaife except an adaptor is not needed.
Crown wheel removal and refitting is not and easy job as in original form they are an interferance fit.
Steve